# use the sum of difference formula what is sin(pi/2-5pi/3)?

31,729 questions
1. ## Pre Calculus

use the sum of difference formula what is sin(pi/2-5pi/3)?

asked by Josh on July 14, 2011

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 pi/4 = sqr2/2 2sin^x(sqrt2/2) = -1 sin x = -sqrt2 x = 7pi/4 and 5pi/4 Am I correct?

asked by Abbey on March 17, 2010

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
4. ## 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
5. ## Calculus

Find the area in the first quadrant bounded by the arc of the circle described by the polar equation r = (2 sin theta)+(4 cos theta) A. 5pi/2 B. (5pi/2)+4 C. 5pi D. 5pi + 8

asked by Tracy on November 21, 2011
6. ## math

need an aswer quich ok thiers two the find sin(2pi/3 -pi/4) using sum and difference identites and then tan 5pi/12 using the same identites

asked by robert on August 3, 2009
7. ## precalculus

Is this right? Convert the polar coordinate (-14, 5pi/3) to rectangular form. Does it mean rectangular coordinates and if so can you check my work? answer: r=-14 theta=5pi/3 x=-14 cos 5pi/3 x=-14(0.5) x=-7 y=rsintheta y=-14 sin 5pi/3 y=-14(-0.866) y=12.124

asked by Anonymous on December 12, 2016
8. ## 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
9. ## Math

1. On the interval [0, 2pi] what are the solutions to the equation sin3xcos2x = -cos3xsin2x + 1? pi/10 and pi/2? 2. What is the value of tan75degrees? √(3) + 1)/(1 - √(3))? 3. Value of cos(130degrees)cos(130degrees) + sin(10degrees)sin(10degrees)? Not

asked by mysterychicken on June 3, 2013
10. ## Calculus

find the exact value of sin 11pi/12 using the sum or difference formula.

asked by Josh on July 19, 2011
11. ## Math Homework

I'm really confused on how to do this. Can someone show me step by step on how to solve this? The directions say to use the Sum-to-Product formulas to find the exact value of the expression. sin 5pi/4-sin 3pi/4

asked by Rachel on February 3, 2015
12. ## Trig functions

1)Write the equation sin y= x in the form of an inverse function. A)y=Sin-1x B)x=Sin-1y C)y=sin-1x D)y=Sinx I chose A 2)Solve y=Arcsin1/2 A)-5pi/6 B)5pi/6 C)-pi/6 D)pi/6 I chose D 3)Find the value of Sin-1(-1/2) A)-30 degrees B)30 degrees C)150 degrees

asked by Jon on February 12, 2008
13. ## Math - complex numbers

These questions are related to de moivre's theorem: z^n + 1/z^n = 2cosntheta z^n - 1/z^n = 2 isin ntheta 1. Express sin^5theta in the form Asintheta + Bsin3theta + Csin5theta and hence find the integral of sin^5theta. 2. Express sin^6theta in multiples of

asked by Chiquesta on December 17, 2011

Approximate the equation's solutions in the interval (0,2pi) sin2x sinx = cosx 2cos(x) (1/2-sin^2x) = 0 Then I got 3pi/2, pi/2, pi/6 and 5pi/6 Then I substituted 0-3 and got 3pi/2 , 5pi/2 , 9pi/2 , pi/2, pi/6, 7pi/6, 13pi/6 , 19pi/6 , 5pi/6 , 11pi/6 ,

asked by Abbey on March 11, 2010
15. ## Math

Find the quotient 3(cos (5pi/12) + i sin (5pi/12) / 6(cos (pi/12) i sin (pi/12)). Express the quotient in rectangular form. I have no idea what I did but I got (1/4) - 433i/1000.

asked by Jeremy on August 17, 2009
16. ## calculus

Find the exact value of the given expression using a sum or difference formula. sin 345° Can you help with this? I got 1/4 (squareroot 2 - square root 6)

asked by megan on July 11, 2016
17. ## Calculus

Find the area under one arch of a cycloid describe by the parametric equations x=3(2Theta - sin 2Theta) and y= 3(1-cos2Theta). Use 0 and pi for the limiting values of Theta. A. 9Pi B. 18Pi C. 27Pi D. 36Pi Find the area in the first quadrant bounded by the

asked by Anonymous on August 7, 2012
18. ## Algebra 2

What values for theta(0

Find all the soultions of the equation in the interval (0,2pi) sin 2x = -sqrt3 /2 sin -sqrt3 /2 is 4pi/3 and 5pi/3 in the unit circle 2x= 4pi/3 + 2npi 2x=5pi/3 + 2npi I do not know what to do at this point

asked by Hannah on February 17, 2010
20. ## Pre-Cal

Find all the soultions of the equation in the interval (0,2pi) sin 2x = -sqrt3 /2 sin -sqrt3 /2 is 4pi/3 and 5pi/3 in the unit circle 2x= 4pi/3 + 2npi 2x=5pi/3 + 2npi I do not know what to do at this point.

asked by Hannah on February 17, 2010

1. Find the modulus and argument of the following complex numbers, and write them in trigonometric form: a. 5 – 8i Answer = Sqrt{89} ( cos (-1.01219701) + i sin ( -1.01219701)) b. –1 – i answer = Sqrt2 (cos (5pi/4) + i sin (5pi/4)) c. –5 + 12i

asked by Anonymous on May 24, 2018
22. ## pre calc

Use the sum-to-product formula to simplify the expression: If sin 52 + sin 8 = sin A, 0

asked by dylan on April 21, 2013
23. ## Trig/PreCalc

Teach me how to express 5sqrt3 - 5i in polar form please. I don't want you to do the work for me. Just show me the steps I need to do the work properly on my own. Otherwise I will not pass this class or the exam when I enter college, and I do not want to

asked by tabby on April 13, 2012
24. ## Math/Precal

How do i find the exact value for (Cos 5pi/16)(Cos pi/16) + (sin 5pi/16)(sin pi/16)

asked by Cherry on March 18, 2016

1) Find all the solutions of the equation in the interval (0,2pi). sin 2x = -sqrt3/2 I know that the angles are 4pi/3 and 5pi/3 and then since it is sin I add 2npi to them. 2x = 4pi/6 + 2npi 2x = 5pi/3 + 2npi Now I know that I have to divide by 2 but that

asked by Hannah on February 18, 2010

1) Find all the solutions of the equation in the interval (0,2pi). sin 2x = -sqrt3/2 I know that the angles are 4pi/3 and 5pi/3 and then since it is sin I add 2npi to them. 2x = 4pi/6 + 2npi 2x = 5pi/3 + 2npi Now I know that I have to divide by 2 but that

asked by Hannah on February 18, 2010
27. ## Math

Prove that sin 13pi/3.sin 8pi/3+cos 2pi/3.sin 5pi /6=1/2.

asked by Latasha. on June 21, 2018
28. ## Math

Solve (sinx-1)(cosx -1/2) = 0 where 0≤x

asked by Jake on January 25, 2012
29. ## Math III

What values for theta(0

asked by Bryce on December 7, 2018
30. ## math, calculus

Interference Two identical tuning forks are struck, one a fraction of a second after the other. The sounds produced are modeled by f1(t) = C sin ωt and f2(t) = C sin(ωt + α). The two sound waves interfere to produce a single sound modeled by the sum of

asked by MaryJane on June 22, 2018
31. ## math

Use the exact values of the sin, cos and tan of pi/3 and pi/6, and the symmetry of the graphs of sin, cos and tan, to find the exact values of si -pi/6, cos 5/3pi and tan 4pi/3. I have found the answers to the first three using the special tables

asked by jenny on August 24, 2011
32. ## math

Use the exact values of the sin, cos and tan of pi/3 and pi/6, and the symmetry of the graphs of sin, cos and tan, to find the exact values of sin -pi/6, cos 5/3pi and tan 4pi/3. I have found the answers to the first three using the special tables sin pi/6

asked by jenny on August 25, 2011
33. ## math;)

Show that sin(x+pi)=-sinx. So far, I used the sum formula for sin which is sin(a+b)=sin a cos b+cos a sin b. sin(x+pi)=sin x cos pi+cos x sin pi I think I am supposed to do this next, but I am not sure. sin(x+pi)=sin x cos x+sin pi cos pi If that is right

asked by girly girl on April 27, 2018
34. ## 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
35. ## Trig

Given: sin x = 4/5, 0 < x < π/2 sin y = 5/13, π/2 < y < π Find the exact value of sin(x + y) I presume I'm supposed to use the sum and difference formulas but I'm not sure how to get the exactly value of cos x or cos y

asked by R on January 4, 2017
36. ## math

use exact values of the sin,cos and tan of (pi/3) and (pi/6)(which I have found)and the symmetry of the graphs of sin,cos and tan to find the exact values of sin(-pi/6), cos(5pi/3) and tan (4pi/3). I know that sin -(pi/6) = -1/2 and cos (5pi/30 = 1/2 and

asked by jenny on August 23, 2011
37. ## trigonometry

14. Solve sin 2x + sin x = 0 for 0 ≤ x ≤ 2π. 21. Write 2sin37°sin26° as a sum (or difference).

asked by george on January 1, 2013
38. ## another precal

i have two questions for you to check please! 6cos^2x+5cosx-4=0 where 0degrees < or equal to 0 which is < or equal to 360. I got that this factors to (3x+4)(2x-1) so the answer is x= -4/3 and x= 1/2 ?? right? and the second question: determine sin2theta,

asked by justy on May 14, 2007
39. ## Calc

Find the exact total of the areas bounded by the following functions: f(x) = sinx g(x) = cosx x = 0 x = 2pi I set my calculator to graph on the x-axis as a 2pi scale. The two functions appear to cross three times between x = 0 and 2pi. (including 2pi) Now,

asked by Sarah on April 21, 2007
40. ## Math

Hi I was just wondering how do you do inverse functions? example: Sin^-1 (5pi/6) Sin^-1 (3pi/2) Why does most of the answers only have 1 answer and is out of "RANGE"?

asked by Xi on June 10, 2009
41. ## math

use exact values of the sin,cos and tan of (pi/3) and (pi/6)(which I have found)and the symmetry of the graphs of sin,cos and tan to find the exact values of sin(-pi/6), cos(5pi/3) and tan (4pi/3). I know that sin -(pi/6) = -1/2 and cos (5pi/30 = 1/2 and

asked by jenny on August 24, 2011
42. ## Calculus

Find the polar coordinates for point P which has Cartesian coordinates (1,-√3) a) (1,5pi/6) b) (1,5pi/3) c) (√3,5pi/3) d) (2,5pi/3)

asked by Alice on April 4, 2019
43. ## Calculus

Use a Riemann sum with n = 3 terms and the right endpoint rule to approx. ∫(1, 2) sin(1/x)dx. My teacher just needs the terms written out, no need to add or multiply. This is a problem she did up on the board, so here's her answer: sin(4/3)(1/3) +

asked by Justin on November 4, 2015
44. ## trig

Express sin 3x sin 7x as a sum or difference

asked by Steve on December 16, 2009
45. ## Math Work

Can someone please help me with this? Thanks! :) Directions: Use the Product-to-Sun formulas to write the product as a sun or difference. 4cos pi/3 sin 5pi/6

asked by Abby on February 3, 2015
46. ## 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
47. ## math

Evaluate. 1. sin^-1(-1/2) 2. cos^-1[(-root 3)/2] 3. arctan[(root3)/3] 4. cos(arccos2/3) 5. arcsin(sin 2pi) 6. sin(arccos 1) I got these values as my answers: 1. -pi/6 2. 5pi/6 3. pi/6 4. 2/3 5. 2pi 6. 0 Can someone please tell me if they are right? thank

asked by anonymous on January 7, 2010
48. ## calculus

Interference Two identical tuning forks are struck, one a fraction of a second after the other. The sounds produced are modeled by f1(t) = C sin(wt) and f2(t) = C sin(wt + Alpha). The two sound waves interfere to produce a single sound modeled by the sum

asked by Yasha on April 15, 2012
49. ## Math (Calc)

Find the Exact value of Pi/24. I'm not sure whether to use a half-angle formula or a difference/sum of angles formula.

asked by Bryan on December 9, 2007
50. ## Math

use the sum and difference identities to find the cosine angle cos pi/9 cos pi/3 - sin pi/9 sin pi/3 I do not know how to solve this because pi/9 is not on the unit circle.

asked by Hannah on March 17, 2010
51. ## trig

using the fact that 5pi/8=1/2(5pi/8) and the half angle identity for cos to find the exact (in terms of radicals) value of cos(5pi/8)

asked by charly on April 14, 2010
52. ## Trigonometry

Can you show steps on deriving the identity from the sum and difference formulas for cosine: sin a sin b = (1 / 2)[cos(a – b) – cos(a + b)]

asked by Tim on May 10, 2015
53. ## Math

Find the solution. 1. sqrt2 sin x + 1 = 0 My ans: x = 5pi/4 + 2npi and 7pi/4 + 2npi 2. sec x - 2 = 0 My ans: x = pi/3 + 2npi and 5pi/3 + 2npi

asked by Anonymous on October 25, 2015
54. ## Math - Excel

Hi, I need to write an Excel formula and I am trying to double check my work. We are asked to find the difference and relative difference for this account. So the values are: \$10,000 \$10,700 \$11,400 \$12,100 \$12,800 \$13,500 etc. The difference for each is

asked by Carly on September 19, 2016

This is a reply to the question posted here http://www.jiskha.com/display.cgi?id=1178989522 As I explained there, you can find the parameters by defining: x1 = Sin(0.49 t) x2 = Cos(0.49 t) and treat this as an ordinary linear regression problem. If we

asked by Count Iblis on May 13, 2007
56. ## Reiny (this was the one you helped me with)

I tried to explain it by using the arrangement of billiard balls, but I guess you don't play pool. let me try to "draw" the billiard balls . . .o . . o o . .o o o . o o o o o o o o o o sum of one row = 1 sum of two rows = 3 sum of three rows = 6 sum of

asked by Keira on June 27, 2009
57. ## Statistics

To do inferential procedures comparing two proportions, we need another variance formula (our ruler). This formula is based on what principle? A) The variance of the difference of two statistics is the difference of the variances of each statistic. B) The

asked by Katie on November 15, 2013
58. ## calc

find integral using table of integrals ) integral sin^4xdx this the formula i used integral sin^n xdx =-1/n sin^n-1xcosx +n-1/n integral sin^n-2 using the formula this is what i got: integral sin^4xdx=-1/4sin^3xcosx+3/4 integral sin^2xdx= -1/2sinxcosx+1/2

asked by tom on February 20, 2011
59. ## Math

Use the product-to-sum formulas to write the product as a sum or difference. sin(x+y) * cos(x-y)

asked by Anonymous on October 27, 2015
60. ## precalc

use the sum to product formula to simplify sin 42degrees+sin 18 degrees=sin A degrees 0

asked by roger on April 1, 2016
61. ## pre calcalus

evaluate sin(-5pi/9)

asked by gion on December 3, 2009
62. ## Precalculus check answers help!

1. Which expression is equivalent to cos 2theta for all values of theta ? cos^2 theta – sin^2 theta ~ cos^2 theta – 1 1 – 2 sin^2 theta 2 sin theta cos theta 2. Use a half–angle identity to find the exact value of sin 105°. -1/2(sqrt)(2 + Sqrt3)

asked by Kelsey on May 28, 2012

sin(x+(pi/4))- sin(x-(pi/4))=1 1. Apply the sum and difference formulas for sine to simplify the left-hand side of the equation. 2. find all the solutions you found to the equation you found.

asked by Alisa on January 29, 2014
64. ## Pre-Calculus

How do I solve the equation: 3 = 2.1 sin[(pi/6)t - 5pi/6] + 3.2

asked by Brian on February 19, 2017
65. ## trig

How do you find the exact value of sin 5pi/8?

asked by Sierra on November 7, 2012
66. ## Pre-calculus

Evaluate sin 7pi/12. Using sum, difference, and cofunction identities

asked by Liv on October 15, 2016
67. ## trig

1. 3cot^2 (x) - 1 = 0 My answer: pi/3, 2pi/3, 4pi/3, 5pi/3 2. 4cos^2 (x) - 1 = 0 My answer: pi/3, 2pi/3, 5pi/3, 4pi/3 3. 2sin (x) + csc (x) = 0 My answer: unknown lol i got to the part: sin^2 (x) = -1/2 4. 4sin^3 (x) + 2sin^2 (x) - 2sin^2 (x) = 1

asked by Wanda on May 9, 2008
68. ## maths

Use the product-to-sum formula to write the given product as a sum or difference. 6sin π/10 cos π/ 10

asked by elise on July 11, 2016
69. ## Trigonometry

Show algebraically how to confirm that cos2x=cos^2x-sin^2x using the sum and difference identities

asked by Nikki on July 15, 2012
70. ## trig

find the exact value by using the appropriate half-angle identity: sin(5pi/12)

asked by Sandy on June 6, 2010
71. ## math

Can someone please check my answers and help me with the last question! 1. Solve sin2xcos2x = 4sin2x on the interval [0, 2pi] 0, pi, 2pi? 2. Exact value of sin(pi/12) - sin(5pi/12) root3/4? 3. Using factorial notation, 0! = 1 False? 4. Find the area of the

asked by mysterychicken on June 6, 2013
72. ## math

Factor using the formula for the sum or difference of two cubes. x^6 - 27y^3

asked by Anonymous on March 10, 2010

Use a sum or difference identity to find the exact value of sin 255 degrees Answer: sqrt6-sqrt2/4 Thanks

asked by Lucy on August 30, 2008
74. ## PRE CALC

Which combination of limit properties is required to evaluate this limit? lim (24/x-2x+2)^3 x->4 f. sum, difference, product, root g. sum, difference, product, power h. sum, difference, quotient, power i. sum, difference, quotient, root j. A limit does not

asked by DARRON on November 27, 2012
75. ## Math - PreCalc (12th Grade)

Which combination of limit properties is required to evaluate this limit? lim x->((24/x)-2x+2)^3 A) sum, difference, product, root B) sum, difference, product, power C) sum, difference, quotient, power D) sum, difference, quotient, root E) A limit does not

asked by Shawna on March 20, 2014
76. ## trig

Cos(-11/12) use the sum or difference formula to find the exact number

asked by Lauren on November 13, 2011
77. ## Trigonometry

How to memorize the sum-to-product and product-to-sum formulae more easily ?? I know how to deduce the formula but when i try to memorize it, its so hard. Always sin, cos, a+b, a-b, i always get confused. Is there any way to memorize more efficiently??

asked by Tommy on July 21, 2008

1. cos^-1((-sqrt3)/2) 5pi/6 2. arccos(cos7pi/2) -pi/2 3. sin^-1(sin7pi/4) -pi/4 4. csc(arctan11/60) 61/11

asked by Anonymous on September 30, 2015
79. ## Math

Which angles are coterminal with pi/6? Chose all answers that are correct. A. 5pi/6 B.13pi/6 C.-5pi/6 D.-11pi/6 I think its A and C

asked by Kaylen on February 12, 2016
80. ## trigonometry

5. If cot 2θ = 5/12 with 0 ≤ 2θ ≤ π , find cosθ, sinθ, and tanθ 8. Find the exact value of sin2a if cosa = 4/5(a in Quadrant I) 13. Find the exact value of tan2 if sinB = 5/13 (B in quadrant II) 14. Solve sin 2x + sin x = 0 for 0 ≤ x ≤

asked by Alonso on December 18, 2012
81. ## 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
82. ## Trig

can you please simplify these in faction form? (pi/3) +1=? (2pi/3) +1=? (3pi/4) +1=? (5pi/4) +1=? (5pi/3) +1=? thank you so much!

asked by BreAnne on February 3, 2012
83. ## Math

Write z = 2(sqrt)2 + 2(sqrt)2i in polar form. z = 4(sqrt)2 (cos pi/4 + i sin pi/4) z = 4 (cos pi/4 + i sin pi/4) z = 4 (cos 5pi/4 + i sin 5pi/4) z = 4 (cos pi/2 + i sin pi/2) Write z = -6i in polar form. z = 6 cis 3pi/2 z = 6 cis pi/2 z = -6 cis 3pi/2 x =

asked by Max on April 28, 2018
84. ## trig

A triangle T has vertices P, Q and R. The length of the edge between P and Q is 10, and the angles at P and Q are 60degree and 45degree respectively. What is the radian measure of the angle at R? (A) 5pi/24 (B) 5/24 (C) 5pi/12 (D) 5/12 (E) None of the

asked by minh on May 7, 2011
85. ## Math - Linear Approximation

a) Find a linear approximation of y=sinx at x=pi/6 b) use part (a) to approximate sin(61pi/360) and sin(59pi/360) I just really have no idea how to approach this problem. I know the formula is y=f(a)+f'(a)(x-a). Does that mean it would be

asked by Jamie on March 2, 2017
86. ## Pre-Calc

Find the exact value of sin345 degrees using a sum or difference formula. I got (-sqrt6 + sqrt2)/4. Is this right?

asked by Anonymous on January 20, 2016
87. ## pre-calculus

use a sum or difference formula to find the exact of the trigonometric function cos(-13pi/12)

asked by lina on April 3, 2012
88. ## calculus

For large values of n, the Riemann sum 1/n(sin0 + (pi/2n) + sin(2pi/2n) +sin(3pi/2n)+...sin((n-1)pi/2n)) is an approximation for which of the following integrals?

asked by Anonymous on April 7, 2011

these must be written as a single trig expression, in the form sin ax or cos bx. a)2 sin 4x cos4x b)2 cos^2 3x-1 c)1-2 sin^2 4x I need to learn this!! if you can show me the steps and solve it so I can learn I'd be grateful!!! 1) apply the formula for sin

asked by jim on November 1, 2006
90. ## Trigonometry

I need help with I just can't seem to get anywhere. this is as far as I have got: Solve for b arcsin(b)+ 2arctan(b)=pi arcsin(b)=pi-2arctan(b) b=sin(pi-2arctan(b)) Sub in Sin difference identity let 2U=(2arctan(b)) sin(a-b)=sinacosb-cosasinb

asked by Jen on July 27, 2007
91. ## Derivative

what is the derivative of sin(x^(1/2)) and (sin(x))^(1/2)? Is there a difference? Thanks! Yes, there is a difference. Use the chain rule.

asked by Jin on September 24, 2006
92. ## 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
93. ## math

For an arithmetic sequence, a_{19} = 78. If the common difference is -3, find a_1 = (i found it to be 132) the sum of the first 57 terms =?? -I know there is a formula but i cant think of what it is

asked by Ellie on October 25, 2009
94. ## precalculus

Use Demoivre's theorem to find the indicated power of the complex number. Write the result in standard form. 1.(3(cos5pi/4+i sin 5pi/4))^8 2.(3-3i)^6

asked by Susan on November 26, 2016
95. ## PRE CAL SEQUENCES

Given the following finite sum 1/(1*2)+1/(2*3)+1/(3*4)+1/(4*5)+....+1/(n(n+1)) a) Find the first 5 partial sums b) Make a conjecture for a formula for the sum of the first n terms c) Use mathematical induction to prove your formula

asked by jack on April 12, 2010
96. ## algebra1

find each sum,difference,or product. If the sum or difference does not exist, write impossible. if A=[5 2 -7 B=[2 9 -3 C=[-4 2 D=[37 22 -1 0 13 12 4 7 9 7 -5 12 3 8 6] -6 -2 5] 15 33] 11 0] 1.A+B 2.B+C 3.C+D 4.D-B 5.A-B 6.D-C 7.2D 8.4B 9.-3A 10.3C

asked by QP on September 15, 2010
97. ## Trig hep, please? Thank you!

1. Find the exact value of sin(195(degrees)) 2. If cot2(delta)=5/12 with 0(

asked by Michelle on August 17, 2013
98. ## mathematics-Algebra

I think of two whole numbers;the product of the average of the sum and difference of the numbers and the difference of the sum and difference of the numbers is 12.if three times the first added to the second makes up 11..find the two numbers please show

asked by p1 on March 20, 2016
99. ## Maths

Find the Taylor formula up to n=3 for f(x)=sin(x) at X0=pi/3: sin(x)=a0+a1(x-pi/3)+a2(x-pi/3)^2+a3(x-pi/3)^3+R3 Use this formula to find the approximate value of sin(58 degees)

asked by Chan on April 6, 2017
100. ## PreCal

Can someone tell show me how to do this. Show the product as a sum or difference sin 6x cos 2x

asked by Jay on November 20, 2007