# 1.Write the expression as a sum or difference. cos(5x)cos(-4x) 2.Write the expression as a product. cos(4x)-cos(12x)

62,645 questions
1. ## Precalculus

1.Write the expression as a sum or difference. cos(5x)cos(-4x) 2.Write the expression as a product. cos(4x)-cos(12x)

asked by Anonymous on December 6, 2010
2. ## Precalculus

1.Write the expression as a sum or difference. cos(5x)cos(-4x) 2.Write the expression as a product. cos(4x)-cos(12x)

asked by Lynette on December 5, 2010
3. ## Math

1. use the suitable product-to-sum formula to rewrite the following expression: sin(13x/2)sin(5x/2) 2. Find value of cos(255degrees)cos(105degrees) is it 1/4? 3. cos(pi/12) - cos(5pi/12) root3/4? 4. Use the appropriate sum-to-product formula to rewrite the

asked by mysterychicken on June 3, 2013
4. ## Math

Can someone please check my answers! 2. Find value of cos(255degrees)cos(105degrees) root3 - 2 / 4 3. cos(pi/12) - cos(5pi/12) Is it root3/4? 4. Use the appropriate sum-to-product formula to rewrite the expression sin6x - sin9x I don't really understand

asked by mysterychicken on June 3, 2013
5. ## pre-cal

Simplify the given expression........? (2sin2x)(cos6x) sin 2x and cos 6x can be expressed as a series of terms that involve sin x or cos x only, but the end result is not a simplification. sin 2x = 2 sinx cosx cos 6x = 32 cos^6 x -48 cos^4 x + 18 cos^2 x -

asked by ethan on May 17, 2007
6. ## TRIG!

Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6 x=1 - (3/4)sin^2 2x work on one side only! Responses Trig please help! - Reiny, Monday, February 23, 2009 at 4:27pm LS looks like the sum of cubes sin^6 x + cos^6 x = (sin^2x)^3 +

asked by hayden on February 23, 2009
7. ## Math

Write the expression in terms of costheta and then simplify. cos^4theta - sin^4theta + sin^2theta Ans: cos^4 θ - 1 - cos^4 θ + 1 - cos^2 θ = -cos^2 θ

asked by Anonymous on June 2, 2015
8. ## Trigonometry

Use a sum of difference identity to write the expression as a single function theta: cos(theta - pi). Okay so I know we will use cosAcosA+sinBsinB I got: cos(theta)cos(theta)sin(pi)sin(pi) I don't know how to solve from here and I'm not sure if that is

asked by Abby on February 29, 2016
9. ## Pre-Cal (Trig) Help?

The following relationship is known to be true for two angles A and B: cos(A)cos(B)-sin(A)sin(B)=0.957269 Express A in terms of the angle B. Work in degrees and report numeric values accurate to 2 decimal places. So I'm pretty lost on how to even begin

asked by Giovanni on May 6, 2016
10. ## Trigonometry

Write equivalent equations in the form of inverse functions for a.)x=y+cos è b.)cosy=x^2 (can you show how you would solve) a.) x= y+ cos è cos è = x-y theta = cos^-1(x-y) b.) cosy=x^2 cos(y) = x^2 y = Cos^-1(x^2)

asked by anon on March 3, 2011
11. ## algebra

Can someone please help me do this problem? That would be great! Simplify the expression: sin theta + cos theta * cot theta I'll use A for theta. Cot A = sin A / cos A Therefore: sin A + (cos A * sin A / cos A) = sin A + sin A = 2 sin A I hope this will

asked by Valerie on February 18, 2007
12. ## Algebra

Write an equation for the translation of the function. y = cos x; translated 6 units up A. y = cos x- ­ 6 B. y = cos(x + 6) C. y = cos x + 6 D. y = cos(x ­ 6) I think its B or c..

asked by Veronika on February 23, 2016
13. ## Pre-Calc

I am really struggling with how to do these problems, I posted them a few minutes ago but the answers/work shown was incorrect. 1) a) Use an Addition or Subtraction Formula to write the expression as a trigonometric function of one number. cos 12° cos

asked by Alyssa on April 13, 2015

Use the fundamental identities to simplify the expression. tan^2 Q / sec^2 Q sin^2/cos^2 / 1/cos^2 = sin^2 / cos^2 times cos^2 / 1 = The cos^2 cancels out so sin^2 is left. Is this correct?

asked by Hannah on March 5, 2010
15. ## trig

I have these sum and product property problems and I just want to make sure my work is right. Write equations expressing 1. cos 37degrees cos99degrees as a sum Answer: sin136+(-62) 2. sin4+sin7 as a product Answer: 2sin5.5 sin-1.5 3. cos 8x - cos 2x as a

asked by Kevin on November 11, 2011
16. ## Trig

I have these sum and product property problems and I just want to make sure my work is right. Write equations expressing 1. cos 37degrees cos99degrees as a sum Answer: sin136+(-62) 2. sin4+sin7 as a product Answer: 2sin5.5 sin-1.5 3. cos 8x - cos 2x as a

asked by Kevin on November 13, 2011
17. ## math

Determine exact value of cos(cos^-1(19 pi)). is this the cos (a+b)= cos a cos b- sina sin b? or is it something different. When plugging it in the calculator, do we enter it with cos and then the (cos^-1(19 pi)).

asked by Anonymous on April 14, 2012
18. ## math

Find the exact value of cos 300 degrees. thanks guys cos 300 = 1/2 = 0.500 how do you know? I am supposed to show my work. You ought to know the rule on 30-60-90 triangles. If the hyp is 2, the shorter side is 1, and the longer side is sqrt3. what does

asked by Bill on June 2, 2007
19. ## Precalculus

Solve Cos^2(x)+cos(x)=cos(2x). Give exact answers within the interval [0,2π) Ive got the equation down to -cos^2(x)+cos(x)+1=0 or and it can be simplified too sin^2(x)+cos(x)=0 If you could tell me where to go from either of these two, it would be great

asked by Josh on February 23, 2012
20. ## Math

Write the expression as the sine, cosine, or tangent of an angle. cos 0.96 cos 0.42 + sin 0.96 sin 0.42 Is this cos 0.54?

asked by Anonymous on October 25, 2015
21. ## maths

Find the roots of z^6 + 1 and hence resolve z^6 + 1into read quadratic factors; deduce that cos3x = 4[cos(x) -cos(pi/6)][(cos(x) -cos(pi/2)][(cos(x) -cos(5pi/6)]

asked by jake on November 10, 2008
22. ## maths

Find the roots of z^6 + 1 and hence resolve z^6 + 1into read quadratic factors; deduce that cos3x = 4[cos(x) -cos(pi/6)][(cos(x) -cos(pi/2)][(cos(x) -cos(5pi/6)]

asked by jake on November 10, 2008
23. ## calculus

Differentiate. y= (cos x)^x u= cos x du= -sin x dx ln y = ln(cos x)^x ln y = x ln(cos x) (dy/dx)/(y)= ln(cos x) (dy/dx)= y ln(cos x) = (cos x)^x * (ln cos x) (dx/du)= x(cos x)^(x-1) * (-sin x) = - x sin(x)cos^(x-1)(x) (dy/dx)-(dx/du)=

asked by Chelsea on March 10, 2011
24. ## Calc.

Differentiate. y= (cos x)^x u= cos x du= -sin x dx ln y = ln(cos x)^x ln y = x ln(cos x) (dy/dx)/(y)= ln(cos x) (dy/dx)= y ln(cos x) = (cos x)^x * (ln cos x) (dx/du)= x(cos x)^(x-1) * (-sin x) = - x sin(x)cos^(x-1)(x) (dy/dx)-(dx/du)=

asked by Chelsea on March 9, 2011
25. ## K

(a) Find the indeﬁnite integrals of the following functions. (i) f (t) = 6 cos(3t) + 5e^−10t (ii) g(x) = 21-12x^3/ x (x > 0) (iii) h(u) = cos^2( 1/8 u) (b) Evaluate: (this big F sign at the start, 5 at the top and 1 at the bottom) 5 1/4x (7 + 6x^2) dx

asked by maths on March 24, 2008
26. ## Pre-Calc

1) Use an Addition or Subtraction Formula to write the expression as a trigonometric function of one number. cos 12° cos 18° − sin 12° sin 18° And Find its exact value. 2) Use an Addition or Subtraction Formula to write the expression as a

asked by Alyssa on April 13, 2015
27. ## Trig/Precalc

So I have two questions that have been puzzling me for quite some time and would really appreciate any help with either of them! (a) There are four positive intergers a, b, c, and d such that 4cos(x)cos(2x)cos(4x)=cos(ax)+cos(bx)+cos(cx)+cos(dx) for all

asked by majorbill on January 4, 2015
28. ## Math - Solving Trig Equations

What am I doing wrong? Equation: sin2x = 2cos2x Answers: 90 and 270 .... My Work: 2sin(x)cos(x) = 2cos(2x) sin(x) cos(x) = cos(2x) sin(x) cos(x) = 2cos^2(x) - 1 cos(x) (+/-)\sqrt{1 - cos^2(x)} = 2cos^2(x) - 1 cos^2(x)(1 - cos^2(x)) = 4cos^4(x) - 4cos^2(x)

asked by Anonymous on November 24, 2007
29. ## Studying for Pre Cal exam

Find the fourth roots of − 1/2 + (square root)3/2 i Write the roots in trigonometric form. A - w 1=cos(35°)+isin(35°) w2 =cos(125°)+isin(125°) w3 =cos(215°)+isin(215°) w4 =cos(305°)+isin(305°) B - w1 =cos(40°)+isin(40°) w2

asked by Lottie on July 13, 2016
30. ## Pre Calc.

Use the sum or difference identity to find the exact value of sin255 degrees. My answer: (-sqrt(2)- sqrt(6)) / (4) Find the value of tan (alpha-beta), if cos alpha= -3/5, sin beta= 5/13, 90

asked by Patrick on April 22, 2009
31. ## Trigonometry

There is an arbitrary triangle with angles A, B, and C and sides of lengths a, b, and c. Angle A is opposite side a. How do I get the formulas: b * cos C + c * cos B = a c * cos A + a * cos C = b a * cos B + b * cos A = c Are these standard trig formulas?

asked by mathstudent on December 15, 2006
32. ## trig

Reduce the following to the sine or cosine of one angle: (i) sin145*cos75 - cos145*sin75 (ii) cos35*cos15 - sin35*sin15 Use the formulae: sin(a+b)= sin(a) cos(b) + cos(a)sin(b) and cos(a+b)= cos(a)cos(b) - sin(a)sin)(b) (1)The quantity = sin(145-75) = sin

asked by Paul C on November 26, 2006
33. ## TRIG/ALGEBRA

1) Find the exact value. Use a sum or difference identity. tan (-15 degrees) 2) Rewrite the following expression as a trigonometric function of a single angle measure. cos 3x cos 4x - sin 3x sine 4x

asked by cheyanne on February 24, 2012
34. ## Mathematics - Trigonometric Identities - Reiny

Mathematics - Trigonometric Identities - Reiny, Friday, November 9, 2007 at 10:30pm (sinx - 1 -cos^2x) (sinx + 1 - cos^2x) should have been (sinx - 1 + cos^2x) (sinx + 1 - cos^2x) and then the next line should be sin^2x + sinx - cos^2xsinx - sinx - 1 +

asked by Anonymous on November 10, 2007
35. ## Mathmatics

a. Use the formulas for lowering powers to rewrite the expression in terms of the first power of cosine: (cos^4)x (or cos*x to the 4th power) b.Use an appropriate Half- Angle Formula to Find the Exact value of the expression: 1. tan 15(Degrees) 2. cos

asked by Tricia on March 3, 2014

a. Use the formulas for lowering powers to rewrite the expression in terms of the first power of cosine: (cos^4)x (or cos*x to the 4th power) b.Use an appropriate Half- Angle Formula to Find the Exact value of the expression: 1. tan 15(Degrees) 2. cos

asked by Tricia on March 3, 2014
37. ## precalculus

write each expression as the sine, cosine or tangent of a double angle. then find the exact value of the expression. a. 2sin 22.5 cos 22.5 b. cos^2 105- sin^2 105

asked by ama on July 6, 2012
38. ## precalc

Find the exact value of each expression, if it exists: the -1 are representing the inverse functions! (a) sin -1 (-√2/2) (b) cos−1 (−1) (c) sin( 􏰀sin−1 (π)􏰁) (d) cos−1􏰀(cos􏰀(−4π􏰁􏰁/ 3)) (e) tan−1 (tan(0.6)) (f) cos−1(

asked by help! on April 17, 2016
39. ## Trigonometry

What is cos (pi/2 - x) secx using the fundamental identities to simplify the expression. I think I have the right answer but I want to check to make sure. Well, cos (pi/2 - x) is something you should've seen already. It's just another name for sin(x).

asked by Rob on October 18, 2006
40. ## Pre-Cal

Write the trigonometric expression in terms of sine and cosine, and then simplify. 1). (csc θ − sin θ)/(cos θ) ____________. 2). Simplify the trigonometric expression. (cos u + 1)/(sin u) + (sin u)/(1 + cos u) ______________.

asked by Amber on July 6, 2016
41. ## Trigonometry (repost Reiny)

at 1:35am I posted ; Write equivalent equations in the form of inverse functions for a.)x=y+cos theta b.)cosy=x^2 my answers were a.) x= y+ cos theta cos theta = x-y theta = cos^-1(x-y) b.) cosy=x^2 cos(y) = x^2 y = Cos^-1(x^2) your post confused me a

asked by anon on March 3, 2011
42. ## calculus

pleaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaasw help can you pleaaaaase help me find the area between y=cos(4x) and y=1-cos(4x) 0

asked by aymal on May 2, 2010
43. ## Maths

Determine the exact expression for the following. - cos(pi/4)=(x/60) I got x=60/√2 Is that correct? Also, I had a lot of trouble with this one: cos(pi/6)=(z/60) I got z=(√3 (60/√2))/2 That doesn't seem right, but I don'r know what I', doing wrong.

asked by Lucy on November 8, 2009

I posted before ; Write equivalent equations in the form of inverse functions for a.)x=y+cos theta b.)cosy=x^2 my answers were a.) x= y+ cos theta cos theta = x-y theta = cos^-1(x-y) b.) cosy=x^2 cos(y) = x^2 y = Cos^-1(x^2) your post confused me a little.

asked by anon on March 4, 2011
45. ## Precalculus

Use one of the identities cos(t + 2πk) = cos t or sin(t + 2πk) = sin t to evaluate each expression. (Enter your answers in exact form.) (a) sin(19π/4) (b) sin(−19π/4) (c) cos(11π) (d) cos(53π/4) (e) tan(−3π/4) (f) cos(π/4) (g) sec(π/6+ 2π)

asked by Kaleen on March 10, 2012
46. ## Math

Eliminate the parameter and write the corresponding rectangular equation whose graph represents the curve. x = sec Q y = cos Q x^2 + y^2 = 1/cos^2 + sin^2/cos^2 = x^2(1 +sin^2) = x^2(2-cos^2) x^2(2-1/x^2) = 2x^2 - 1 x^2 - y^2 = 1 My teacher said to use

asked by Abbey on May 4, 2010
47. ## Trig. Law of Cosines

Show that any triangle with standard labeling... a^2+b^2+c^2/2abc = cos(alpha)/a + cos(beta)/b + cos(gamma)/c I don't get it. Can someone please help me. Start here with the law of cosines: a^2 = b^2 + c^2 -2bc Cos A b^2 = a^2 + c^2 -2ac Cos B c^2 = a^2 +

asked by ashley on December 12, 2006
48. ## tigonometry

expres the following as sums and differences of sines or cosines cos8t * sin2t sin(a+b) = sin(a)cos(b) + cos(a)sin(b) replacing by by -b and using that cos(-b)= cos(b) sin(-b)= -sin(b) gives: sin(a-b) = sin(a)cos(b) - cos(a)sin(b) Add the two equations:

asked by Pablo on November 26, 2006
49. ## Calculus (help Steve plz)

1) if w = , find ||w||? 2) which expression is equivalent to (sin x+1) (sin x -1)? A. Cos^2x B. -cos^2x C. Cos^2x+1 D. Cos^2x-1 E. -cos^2x-1

asked by Breanna on November 28, 2012
50. ## Precal

I do not understand how to do this problem ((sin^3 A + cos^3 A)/(sin A + cos A) ) = 1 - sin A cos A note that all the trig terms are closed right after there A's example sin A cos A = sin (A) cos (A) I wrote it out like this 0 = - sin^6 A - cos^6 A +

asked by Joe on January 14, 2010
51. ## maths

Choose the option that gives an expression for the indefinite integral ʃ (cos(4x) + 2x^2)(sin(4x) − x) dx. In each option, c is an arbitrary constant. Options A cos(4x) + 2x^2 +c B -1/8cos(4x) + 2x^2)^2 +c C 1/4 (sin(4x) − x)^2 + c D (1/(2 (sin(4x)

asked by albert on May 11, 2011
52. ## Pre Calculus

Use one of the identities cos(t + 2ðk) = cos t or sin(t + 2ðk) = sin t to evaluate each expression. (Enter your answers in exact form.) (a) sin(17ð/4) (b) sin(−17ð/4) (c) cos(17ð) (d) cos(45ð/4) (e) tan(−3ð/4) (f) cos(7ð/4) (g) sec(ð/6+2ð)

asked by Stephanie823 on March 10, 2012
53. ## Pre Calculus

Use one of the identities cos(t + 2ðk) = cos t or sin(t + 2ðk) = sin t to evaluate each expression. (Enter your answers in exact form.) (a) sin(17ð/4) (b) sin(−17ð/4) (c) cos(17ð) (d) cos(45ð/4) (e) tan(−3ð/4) (f) cos(7ð/4) (g) sec(ð/6+2ð)

asked by Stephanie823 on March 10, 2012
54. ## trig

Show that 1-cos2A/Cos^2*A = tan^2*A 1-cos2A/Cos^2*A = [Cos^2(A) - Cos(2A)]/Cos^2(A). Substitute: Cos(2A) = 2Cos^2(A) - 1: [1 - Cos^2(A)]/Cos^2(A)= Sin^2(A)/Cos^2(A) = tan^2(A)

asked by Paul C on November 26, 2006
55. ## Trig Help!

Question: Trying to find cos π/12, if cos π/6 = square root 3 over 2, how to find cos π/12 using DOUBLE angle formula? This is what I got so far.. cos 2(π/6) = cos (π/6 + π/6) = (cos π/6)(cos π/6) - (sin π/6)(sin π/6) = cos^2 π/6 - sin^2 π/6 Is

asked by Anonymous on April 27, 2012
56. ## math

if cos(B-C)+cos(C-A)+cos(A-B)=-3/2 then prove that cosA+cosB+cosC=O and sinA+sinB+sinC=O after that prove that cos(B-C)=cos(C-A)=cos(A-B)=-1/2

asked by Binoy kumar mahato on October 6, 2017
57. ## Mathematics - Trigonometric Identities

Let y represent theta Prove: 1 + 1/tan^2y = 1/sin^2y My Answer: LS: = 1 + 1/tan^2y = (sin^2y + cos^2y) + 1 /(sin^2y/cos^2y) = (sin^2y + cos^2y) + 1 x (cos^2y/sin^2y) = (sin^2y + cos^2y) + (sin^2y + cos^2y) (cos^2y/sin^2y) = (sin^2y + cos^2y) + (sin^2y +

asked by Anonymous on November 8, 2007
58. ## MATH

Hi, I really need help with these questions. I did some of them halfway, but then I got stuck. Would you please help me? Thank you so much. Prove the identity.... 1. sec x + tan x(1-sin x/cos x)=1 1/cos x + sin x/cos x(cos^2 x/cos x)=1 1+sin x/cos

asked by LIZZIE010 on January 2, 2014

1) Use the cofunction identites to evaluate the expression without the aid of a calculator. cos^2 18 degrees + cos^2 72 degrees. Would I use the forumula cos(pi/2 - Q) = sin Q

asked by Abby on February 28, 2010
60. ## Math

This one confused me since it revolved around what seemed like dividing trig function by another function Write the following expression in terms of the tangent function 2 / ((cos(r^2 - s^2) / (sin(r^2 - s^2)) = ? I know tan t = sin t / cos t. So would I

asked by Taylor on November 14, 2014
61. ## Math - Solving Trig Equations

Solve each equation for o is less than and/or equal to theta is less than and/or equal to 360 -- sin^2x = 1 = cos^2x -- Work: cos^2x - cos^2x = 0 0 = 0 -- Textbook Answers: 90 and 270 -- Btw, how would you isolate for cos^2x = 0? Would it be... x = cos^-1

asked by Anonymous on November 24, 2007

Write each expression in the standard form for a complex number, a + bi. A. [3(cos(27°)) + isin(27°)]^5 B. [2(cos(40°)) + isin(40°)]^6 For A i got 2.67+1.36i and for B i got 1.53+1.29i

asked by Kyle on April 18, 2016
63. ## Trigonometry

Write each expression in the standard form for a complex number, a + bi. A. [3(cos(27°)) + isin(27°)]^5 B. [2(cos(40°)) + isin(40°)]^6 For A i got 2.67+1.36i and for B i got 1.53+1.29i

asked by Kyle on April 18, 2016
64. ## Math - Trigonometry

Let f(x) be a polynomial such that f(cos theta) = cos(4 theta) for all \theta. Find f(x). (This is essentially the same as finding cos(4 theta) in terms of cos theta; we structure the problem this way so that you can answer as a polynomial. Be sure to

asked by Sam on November 6, 2013
65. ## trig help much appreciated! :))

1. Find the complete exact solution of sin x = . 2. Solve cos 2x – 3sin x cos 2x = 0 for the principal value(s) to two decimal places. 3. Solve tan2 x + tan x – 1 = 0 for the principal value(s) to two decimal places. 4. Prove that tan2  – 1 + cos2 

asked by suzy on August 16, 2013
66. ## Math - Solving for Trig Equations

Solve the following equation for 0 less than and/or equal to "x" less than and/or equal to 360 -- cos^2x - 1 = sin^2x -- Attempt: cos^2x - 1 - sin^2x = 0 cos^2x - 1 - (1 - cos^2x) = 0 cos^2x - 1 - 1 + cos^2x = 0 2cos^2x - 2 = 0 (2cos^2x/2)= (-2/2) cos^2x =

asked by Anonymous on November 22, 2007
67. ## math

Write the expression as the sine, cosine, or tangent of an angle. sin(2π/9)cos(3π/8)+cos(2π/9)sin(3π/8)

asked by Stella on June 10, 2018
68. ## Pre-Calculus

Write the following expression as the sine, cosine or tangent of an angle. cos 3x cos 2y + sin 3x sin 2y

asked by Mariam on January 24, 2018
69. ## Math

Explain how to do this with steps please. 1. Simplify cos(x-y)+cos(x+y)/cosx I did some of these so far, don't know if it is correct. Formula: cosxcosy= cos(x+y)+cos(x-y)/2 cos(x-y)+cos(x+y)/cosx =cosxcosy/2cosx

asked by Jake on January 26, 2012
70. ## Math

Solve this equation algebraically: (1-sin x)/cos x = cos x/(1+sin x) --- I know the answer is an identity, and when graphed, it looks like cot x. I just don't know how to get there. I tried multiplying each side by its conjugate, but I still feel stuck.

asked by Momo on October 18, 2009
71. ## find dy/ds

y = s*square root of(1-s^2) + cos inverse(s) Just give me some hints and I will do it. Thanks. You have y = s*square root of(1-s^2) + cos inverse(s) which I would write as y = s*sqrt(1-s2) + cos-1(s) and you want dy/ds For the first term use the product

asked by Jen on October 20, 2006
72. ## Math, derivatives

Let g(x) = sin (cos x^3) Find g ' (x): The choices are a) -3x^2sinx^3cos(cos x^3) b) -3x^2sinx^3sin(cos x^3) c) -3x^2cosx^3sin(cos x^3) d) 3x^2sin^2(cos x^3) I'm not exactly sure where I should start. Should I begin with d/dx of sin? Or do the inside

asked by Marissa on May 11, 2008

ok, i tried to do what you told me but i cant solve it for c because they cancel each others out! the integral for the first one i got is [sin(c)cos(x)-cos(c)sin(x)+sin(x)+c] and the integral for the 2nd one i got is [-sin(c)cos(x)+cos(c)sin(x)-sin(x)+c] I

asked by K on November 29, 2010
74. ## Calculus

which of the following integrals results from making the substitution u=x^3 in orer to find (squiggly vertical line)x^2cos(x^3)dx ~cos u du ~u^2 cos u du ~u^(2/3) cos u du1/3 os u du ~3 cos u du

asked by Ken on May 11, 2012
75. ## math

A trigonmetric polynomial of order n is t(x) = c0 + c1 * cos x + c2 * cos 2x + ... + cn * cos nx + d1 * sin x + d2 * sin 2x + ... + dn * sin nx The output vector space of such a function has the vector basis: { 1, cos x, cos 2x, ..., cos nx, sin x, sin 2x,

asked by mathstudent on January 16, 2008
76. ## trig

The expression 4 sin x cos x is equivalent to which of the following? (Note: sin (x+y) = sin x cos y + cos x sin y) F. 2 sin 2x G. 2 cos 2x H. 2 sin 4x J. 8 sin 2x K. 8 cos 2x Can someone please explain how to do this problem to me?

asked by B.S. on June 12, 2009
77. ## trigonomentry out of ideal help ah!crying

compute.. Cos(1degree)+cos(3degree)+cos(5degree)+...+Cos(179degree) plz show working even an hint can,t help me.Have been do maths alday my brain is fried..Ah thanks

asked by david on April 1, 2016
78. ## calc.- trig substitution

s- integral s 1/ [ (x^4) sq.rt(x^2+9)] i know x=3tanx sq.rt(x^2+9)= 3 secx dx= 3/[cos^2(x)] so far i know: = 1/ (3tan^4(x)) 3secx cos^2(x)) dx =1/ 81 [ (sin^4 (x)/cos^4 (x)) (1/cosx) (cos^2(x))] then i'm not really sure what to do next

asked by christine on February 26, 2007
79. ## trig

it says to verify the following identity, working only on one side: cotx+tanx=cscx*secx Work the left side. cot x + tan x = cos x/sin x + sin x/cos x = (cos^2 x +sin^2x)/(sin x cos x) = 1/(sin x cos x) = 1/sin x * 1/cos x You're almost there. thanks so

asked by Devon on May 7, 2007
80. ## math

Write the given expression as the cosine of an angle. cos 60° cos 65° − sin 60° sin 65°

asked by terry on July 11, 2016
81. ## Trigonometry - LONESTAR

Simplifying steps without using the calculator for: tan(cos^-1(-1/10)) cos(sin^−1(1/x)) Assume x is positive tan(cos^−1(12/13)) cos^−1(cos 150°) This is pretty much the entire section we are doing. My teacher is a robot and has us self teach

asked by Angels on March 3, 2014
82. ## trig

2sin(x)cos(x)+cos(x)=0 I'm looking for exact value solutions in [0, 3π] So I need to find general solutions to solve the equation. But do I eliminate cos(x), like this... 2sin(x)cos(x)+cos(x)=0 2sin(x)cos(x)= -cos(x) 2sin(x) = -1 sin(x) = -1/2 at 4pi/3

asked by Alex on March 23, 2008
83. ## calculus/Trig

Suppose you wish to express sin(3t) in terms of sint and cost. Apply the sum formula to sin(3t) = sin(t+2t) to obtain an expression that contains sin(2t)=sin(t+t) and cos(2t)=cos(t+t). Apply the sum formulas to those two expressions. Enter the resulting

asked by John on May 23, 2010
84. ## pre-calculus

which expression is equivalent to (sinx+1)(sinx-1)? A.) COS^2X B.) -COS^2X C.) COS^2X+1 D.) COS^2X-1 E.) -COS^2X+1

asked by Daisy on July 27, 2015
85. ## CALCULUS

If cos(t)=–7/9, find the values of the following trigonometric functions. Note: Give exact answers, do not use decimal numbers. The answer should be a fraction or an arithmetic expression. a) cos (2t) b) sin (2t) c) cos(1/2) d) sin (1/2) i don't even

asked by Stumped Student on September 22, 2007
86. ## Trig

Given: cos u = 3/5; 0 < u < pi/2 cos v = 5/13; 3pi/2 < v < 2pi Find: sin (v + u) cos (v - u) tan (v + u) First compute or list the cosine and sine of both u and v. Then use the combination rules sin (v + u) = sin u cos v + cos v sin u. cos (v - u) = cos u

asked by Nan on December 29, 2006
87. ## precalculus

I don't understand this problem: (Tanө + cos ө)/ (sec ө + cot ө) so I start off like this: ={(sinө / cos ө)+cosө}{cos ө + (sinө/cosө)} =[(sin ө +cos^2ө) (cos^2ө +sin ө)]/ cos ө but what comes next?

asked by allison on February 22, 2009
88. ## Math

Find the exact value of cos 1 degree + cos 2 degrees + cos 3 degrees + ... + cos 357 + cos 358 degrees + cos 359 degrees.

asked by EC on October 24, 2016
89. ## Math

Explain how to do this with steps please. 1. Simplify cos(x-y)+cos(x+y)/cosx Formula: cosxcosy= cos(x+y)+cos(x-y)/2 cos(x-y)+cos(x+y)/cosx =cosxcosy/2cosx

asked by Jake on January 26, 2012

1)tan Q = -3/4 Find cosQ -3^2 + 4^2 = x^2 9+16 = sqrt 25 = 5 cos = ad/hy = -4/5 Am I correct? 2) Use the sum and difference identites sin[x + pi/4] + sin[x-pi/4] = -1 sinx cospi/4 + cosxsin pi/4 + sinx cos pi/4 - cosx sin pi/4 = -1 2 sin x cos pi/4 =-1 cos

asked by Abbey on March 16, 2010

1.)Find dy/dx when y= Ln (sinh 2x) my answer >> 2coth 2x. 2.)Find dy/dx when sinh 3y=cos 2x A.-2 sin 2x B.-2 sin 2x / sinh 3y C.-2/3tan (2x/3y) D.-2sin2x / 3 cosh 3yz...>> my answer. 2).Find the derivative of y=cos(x^2) with respect to x. A.-sin (2x) B.-2x

asked by anon on March 6, 2011
92. ## Trig (math)

1.) Write the complex number in trigonometric form r(cos theta + i sin theta) with theta in the interval [0°, 360°). 9 sqrt 3 + 9i 2.) Find the product. Write the product in rectangular form, using exact values. [4 cis 30°] [5 cis 120°] 3.) [4(cos

asked by Anonymous on December 7, 2014
93. ## calc

find the area between the x-axis and the graph of the given function over the given interval: y = sqrt(9-x^2) over [-3,3] you need to do integration from -3 to 3. First you find the anti-derivative when you find the anti-derivative you plug in -3 to the

asked by mikayla on April 18, 2007
94. ## trig

how would you verify this trig identity (1+cos(x) / 1-cos(x)) - (1-cos(x) / 1+cos(x)) = 4cot(x)csc(x) ? help please!

asked by amanda on June 25, 2008
95. ## math

Prove that for all real values of a, b, t (theta): (a * cos t + b * sin t)^2

asked by mathstudent on December 19, 2006
96. ## pre calc trig check my work please

sin x + cos x -------------- = ? sin x sin x cos x ----- + ----- = sin x sin x cos x/sin x = cot x this is what i got, the problem is we have a match the expression to the equation work sheet and this is not one of the answers. need to figure out what im

asked by Anna on October 20, 2010
97. ## Math- Trig

1. Determine the exact value of cos^-1 (pi/2). Give number and explanaton. 2. Determine the exact value of tan^-1(sq. root 3). with explanation. 3. Determine exact value of cos(cos^-1(19 pi)). with explanation. 4. Determine the exact value of sin(sin^-1(20

asked by Crystal on April 14, 2012
98. ## Math

Prove each identity: a) 1-cos^2x=tan^2xcos^2x b) cos^2x + 2sin^2x-1 = sin^2x I also tried a question on my own: tan^2x = (1 – cos^2x)/cos^2x R.S.= sin^2x/cos^2x I know that the Pythagorean for that is sin^2x + cos^2x That's all I could do.

asked by Kate on July 18, 2011
99. ## Vector Algebra

Find the direction angles of the vector given below. Then write each vector in the form v = ||v||[(cos A) i + (cos B) i + (cos Y) k ]. v = -6i + 12j + 4k

asked by Rita on February 22, 2008
100. ## trigonometry

express 3 cos x -2 sin x in th eform R cos (x + a) and hence write down the maximum and minimum values of 3 cos x - 2 sin x.

asked by lindsay on April 21, 2012