# If cos(t)=(-7/8) where pi

4,795 questions, page 9-
## Trigg

How do I find a rectangular-coordinate equation for the curve by elimination the parameter? x=2 sin t, y= 4 cos t so far I have x= r cos(theta) and y= r sin (theta) but, it's the opposite. please help.

*asked by Jenny on March 17, 2014* -
## MathsSs triG

Consider sin(x-360)sin(90-x)tan(-x)/cos(90+x) 1.A.SIMPLIFY sin(x-360)sin(90-x)tan(-x)/cos(90+x) to a single trigonometric ratio B.hence or otherwise without using a calculator,solve for X if 0

*asked by katlego ratsoma on October 3, 2013* -
## Calculus

What is the derivative of k(x)=sin x cos x? A. -sin x cos x B. -2 sin x cos x C. 2 cos^2x-1 D. sin^2x - cos^2x

*asked by hhhhh on January 12, 2017* -
## physics

a 17.0kg crate is to be pulled a distance of 20.0m requiring 1210J of work being done. If the job is done by attaching a rope and pulling with a force of 75.0 N, at what angle is the rope held? W=Fd(cos) 1210J=(170)(20m)(cos)

*asked by Anonymous on February 24, 2010* -
## MATH

Differential equations, initial value problem. The general equation of motion is: mx"+Bx'+kx=f(t), where the independent variable is t, and the displacement x is the dependent variable. In this case, external force f(t)=0, so mx"+Bx'+kx=0 substitute

*asked by Anonymous on March 16, 2011* -
## Trigonometry

Hi. I am reposting this. Can you verify. Thanks. (cosθ) / (sinθ – 1) + (cosθ)/ (1 + sinθ) = -2tanθ (1 / cos^2θ) – (2) (1/cos^2θ) (sinθ / cosθ) + (sin^2θ / cos^2θ) = (1 - sinθ) / (1 + sinθ)

*asked by Ashley Kate on March 1, 2014* -
## Calculus

(This problem uses a TI-89 calculator) Find the largest and smallest values of the following function on their given intervals: y=(cos x)^x [-1.5, 4.75] This is what I put in the calculator (home screen): fMin((cos(x))^x,x I -1.5 < x < 4.75 (I = "with"

*asked by Anonymous on June 8, 2009* -
## Calculus (repost)

This problem uses a TI-89 calculator) Find the largest and smallest values of the following function on their given intervals: y=(cos x)^x [-1.5, 4.75] This is what I put in the calculator (home screen): fMin((cos(x))^x,x I -1.5 < x < 4.75 (I = "with"

*asked by Anonymous on June 8, 2009* -
## Pre Cal.

Express 5sqrt(3) - 5i in polar form. A: 10(cos(11pi/6) + i sin(11pi/6)) Express 4(cos(3pi/4) + i sin(3pi/4)) in rectangular form. A: -2sqrt(2) + 2sqrt(2i Write 2x+y=5 in polar form. A: sqrt(5)= r cos (theta-27degrees) Are these correct?

*asked by Jeremy on August 15, 2009* -
## Trig

Find all solutions w between 0 and 360, inclusive: (a) cosw = cos(−340) (b) cosw = sin20 (c) sinw = cos(−10) (d) sinw < − 1 2 (e) 1 < tanw

*asked by Sally K on April 11, 2010* -
## Trig

Find all solutions w between 0 and 360, inclusive: (a) cosw = cos(−340) (b) cosw = sin 20 (c) sinw = cos(−10) (d) sin w < − 1/2 (e) 1 < tanw

*asked by sally on April 12, 2010* -
## maths

Find all possible solutions in the range 0°≤ x ≤ 180° of the following equations: (a) cos x = sqrt(2) / 2 (b) tan x = sqrt(3) / 3 (c) sin x = sin60° (d) cos x = -1/2 (e) sin x = -1/2

*asked by Steven on November 18, 2016* -
## MATHS

Find all possible solutions in the range 0°≤ x ≤ 180° of the following equations: (a) cos x = sqrt(2) / 2 (b) tan x = sqrt(3) / 3 (c) sin x = sin60° (d) cos x = -1/2 (e) sin x = -1/2

*asked by Joshua on November 21, 2016* -
## Quantum Physics

I.Provide a unitary that maps |+> to |1> and |-> to |0> . Enter 0 in all boxes if no such unitary exists. (In this case, you have to enter 0 explicitly. Blanks are not accepted.) a b c d II.Provide a unitary that maps cos (30) |0> + sin (30) |1> to

*asked by Bel on March 15, 2013* -
## Math - Trig - Double Angles

Prove: cos4x = 8cos^4x - 8cos^2x + 1 My Attempt: RS: = 4cos^2x (2cos^2x - 1) + 1 = 4 cos^2x (cos2x) + 1 LS: = cos2(2x) = 2cos^2(2x) - 1 = (cos^2(2)) - cos^2(2x)) - 1 ----- Prove: 8cos^4x = cos4x + 4cos2x + 3 My Attempt: RS: = cos2(2x) + 4cos(2x) + 3 =

*asked by Anonymous on November 17, 2007* -
## Plane Trigonometry

tan A=-4/5;A in Quadrant 2 and cos B=-5/13: B in Quadrant 3. What is the exact value of the expression cos(A+B)?

*asked by Math on November 2, 2016* -
## Pre-Calculus

Given cos A = -3/5, π

*asked by Anonymous on October 24, 2018* -
## math help trigonometry

Prove the following identity tan x cos x/sin x=1/sin x cos x

*asked by lewis on June 10, 2015* -
## math

Find the imaginary part of (cos(12) + i sin(12) + cos(48) + i sin(48))^6.

*asked by Katie on May 28, 2016* -
## Pre calc

Someone please help me prove these A) cos^4x-sin^4x=cos2x B)tanx=sin^2x/1+cos^2x Please and Thank you

*asked by Bethany on April 13, 2017* -
## Pre calc

Someone please help me prove these A) cos^4x-sin^4x=cos2x B)tanx=sin^2x/1+cos^2x Please and Thank you

*asked by Samantha on April 13, 2017* -
## Math

Find all values of x in the interval [0, 2 pi] that satisfy 2 cos x-1 = 0. cos x = 1/2 x = 60 How do I find the other value of x?

*asked by Raj on September 25, 2007* -
## math

Find the exact value of the expression. cos(π/16)cos(3π/16) − sin(π/16) sin(3π/16)

*asked by Stella on June 10, 2018* -
## precalculus

Solve the equation cos(2x)cos(x)+sin(2x)+sin(x)=1 for all values of x.

*asked by marie darling on April 14, 2013* -
## Trig

Verify the Identity (sin m +sin n)/ (cos m + cos n) = tan(m + n/2)

*asked by Steve on October 24, 2009* -
## math

how do I solve this? (cos ө+1)/ (cos ө - 1) The answer is supposed to be: (1 + sec ө)/ (1- sec ө)

*asked by kayla on February 8, 2009* -
## Precalc

Prove or disprove the following identity. cos(-x) - sin(-x) = cos(x) + sin(x)

*asked by George on November 13, 2012* -
## Math

Match the trigonometric expression: cos^2 [(pi/2) - x] / cos x Does csc x match with this?

*asked by Hannah on March 5, 2010* -
## Trigonometry

What are these things called: -cos x = cos -x What are the rules to these trig rules? Thanks

*asked by Trigonometry on January 22, 2012* -
## mth, trig

Given cos a=-7/25 in quadrant II , and sin b=-12/13, in quadrant IV , find cos(a+b) and sin2a

*asked by shay on April 18, 2012* -
## Trig

Prove the identity: (sin(2x-y)+siny)/(cos(2x-y)+cosy )=tanx

*asked by Alexa on July 30, 2015* -
## math

how to find the period of y = cos(6x)from your graph. what is the period of y=cos(6x) in radians?

*asked by subash on April 8, 2010* -
## Precalculus

Find the exact value of: Cos(inverse tan 4/3 + inverse cos 5/13)

*asked by Thomas on April 21, 2014* -
## math

how to find the period of y = cos(6x)from your graph. what is the period of y=cos(6x) in radians?

*asked by subash on April 8, 2010* -
## Trigonometry

Prove that sin(n+1)A-sin(n-1)A/cos(n+1)A+2cosnA+cos(n-1)A = tanA/2

*asked by Kewal on January 5, 2012* -
## math

how do you simplify cos(A+B)*cos B=sin(A+B)*sin B can you show me the steps? thank you very much!!!

*asked by candybar on February 9, 2011* -
## Maths

(Cos/1+cosec) + (sin/ 1+cot ) = sin + cos prove that

*asked by Sanjay on August 19, 2017* -
## maths trigo

prove that sin(n+1)A-sin(n-1)A/cos(n+1)A+2cos(nA)+cos(n-1)A=tanA/2

*asked by ankita on September 30, 2012* -
## Algebra II Part 2

Use an angle sum identity to verify the identity cos 2 0=2 cos 0-1

*asked by Karen on May 18, 2013* -
## pre calc

sin 20 pi cos 9 pi cos 13pi/2 sin(-17 pi0 are all of these undefined?

*asked by jim on January 2, 2012* -
## trigo

Obtain an identity for the first function value in terms of the second function value. cos 3x ; cos x

*asked by rai zan on September 28, 2014* -
## trig

suppose sin(x)=5/6, and x is in the first quadrant. Determine cos(x), sin(2x), and cos(2x).

*asked by jj reddick on October 24, 2010* -
## physics

A dive bomber has a velocity of 290 m/s at an angle θ below the horizontal. When the altitude of the aircraft is 2.15 km, it releases a bomb, which subsequently hits a target on the ground. The magnitude of the displacement from the point of release of

*asked by Spice on October 25, 2015* -
## Algebra II

Multiple Choice Which expression is NOT equivalent to 1? (theta) means 0 with dash in it. A.)sin^2 (theta)+cot^2 (theta) sin^2 (theta) B.)(sin^(theta))/(1-cos(theta))-cos(theta) C,)sec^2 (theta)+ tan^2 (theta) D.)(cot^2(theta) sin^2 (theta))/(cos^2(theta))

*asked by HotMath on June 9, 2011* -
## Calculus

Determine an upper/lower estimate for the area under the curve f(x) = cos x between x = 0 and x = pi/2 . Show how you arrive at this estimate. This is the question that my teacher wanted us to answer and I'm not sure how to even start the process. Should I

*asked by Mia on October 29, 2016* -
## Calculus

Find all points on the graph of the function f(x) = 2 cos(x) + (cos(x))2 at which the tangent line is horizontal. Consider the domain x = [0,2π). I have pi/2 and 3pi/2 for x values. But when I plug them I get zero. Is this correct as y values or am I

*asked by Calculus on January 11, 2016* -
## trigonometry

5. Find the complete exact solution of sin x = -√3/2. 9. Solve cos 2x – 3sin x cos 2x = 0 for the principal value(s) to two decimal places. 21. Solve tan^2x + tan x – 1 = 0 for the principal value(s) to two decimal places. 22. Prove that tan^2a –

*asked by eemily on December 13, 2012* -
## trigonometry

I need help in understanding how to identify which identity to use. using this question as an example. Show that tan theta (sin theta+cot theta cos theata)all over cos theta = sec^2 theta. Please explain.

*asked by lindsay on May 4, 2012* -
## precalculus

Find the tan(x), the sin (x + pi) if it is known that cos (x)=.6 and that (3pi)/2 less than x less than 2pi. Find the sine (2x), the tan (2x), and the cos (x/2) if it is known that cos (x)=.6 and that (3pi)/2 less than x less than 2pi.

*asked by marie darling on April 10, 2013* -
## physics

A block accelerates at 3.3 m/s^2 down a plane inclined at an angle of 26 degrees.Find micro(k) between the block and the inclined plane. The acceleration of gravity is 9.81 m/s^2. This is my work but i am not sure if it is correct: sum of forces on x axis=

*asked by alexa on July 14, 2011* -
## maths

expand each of the following using the compound angle formulae a. cos(A - B) b. sin(alpher + alpher) c. cos(alpher + 70°)

*asked by herMajesty on April 27, 2016* -
## Math Please Help

Eliminate the parameter and sketch the curve. x=cos(theta) , y=cos^2(theta) + 8cos(theta)

*asked by Ally on May 20, 2015* -
## trig

Given sin a = 15/17 with a in Quadrant I and cos beta = 4/5 with beta in QuandrantIV, find the exact value of cos(a+beta)

*asked by MIK on May 17, 2012* -
## Math

Prove the identities 1. cos3Ɵ + cos Ɵ = 4cos^Ɵ - 2 cos Ɵ 2. sin (A+B)sin (A-B)=cos2B + sin^2 A-1

*asked by Anonymous on October 25, 2012* -
## Math

Guys please help me with this Trigonometry question based on De Moivre's theorem. Q: Find ¦È such that 0¡Ü¦È¡Ü360. cos7¦È + cos3¦È = cos5¦È I attempted to solve it with limited knowledge but I kind of doubt my answer. Anyway, this is how I

*asked by Nye on October 16, 2016* -
## Calculus

Consider the curve below. x = (cos(t))^2 y = cos(t) 0 ≤ t ≤ 6π (a) Find the distance traveled by a particle with position (x, y) as t varies in the given time interval. (b) What is the length of the curve? I have no idea on how to evaluate this

*asked by Jed on December 12, 2015* -
## pre-calc

simplfy the expression by double angle formula or a half angle formula. cos^2(x/2)-sin^2(x/2) 2sin(x/2)cos(x/2)

*asked by Amanda on April 22, 2012* -
## trigonometry

1) Perform the operation and leave the result in trig. form. [3/4(cos pi/3 + i sin pi/3)][4(cos 3pi/4 + i sin 3pi/4)] Thanks

*asked by mikey on December 3, 2012* -
## Math

Write the first trigonometric function in terms of the second for θ in the given quadrant. tan(θ), cos(θ); θ in Quadrant IV I believe to start this is 1/cos^2*theta. Am I write? If not, can you please help me?!

*asked by Jennifer on April 14, 2016* -
## Calculus

Integrate 1/sinx dx using the identity sinx=2(sin(x/2)cos(x/2)). I rewrote the integral to 1/2 ∫ 1/(sin(x/2)cos(x/2))dx, but I don't know how to continue. Thanks for the help.

*asked by Andre on January 11, 2016* -
## Trigonometry

Use the power-reducing formulas to rewrite the expression in terms of the first power of the cosine. [#1.] (sin^4x)(cos^4x) [#2.] (sin^4x)(cos^2x)

*asked by Tom on November 29, 2008* -
## maths

Angle a lies in the second quadran and angle b lies in the third quadrant such that cos a = -3/5 and tan b = 24/7. Determine an exact value for cos (a+b), sin(a-b)

*asked by sayan on April 11, 2012* -
## Math

Calculate the integral ∫-2e^(Sin(x)) Cos(x) dx , u = Sin(x) Just having a slight hard time at finding du to solve the integral du: Cos(x) dx

*asked by B-c on October 2, 2018* -
## maths

Prove the following trigonometric identities (i)(1+cotx)^2 +(1-cotx)^2=2cosec^2x (ii)cos(270degrees+theta)/cos(360degrees -theta)

*asked by tembo on February 27, 2012* -
## Math

Find the quotient of the following expression: 7(cos 5pi/6 +isin 5pi/6) / -2(cos pi/2 +isin pi/2) I got -7/4+ 7 square root 3/4 i. Is this correct?

*asked by Anonymous on January 9, 2015* -
## Trig

How do I write cos(11x)cos(x)+sin(11x)sin(x) as a single trigonometric function? Please show steps.

*asked by Anonymous on April 3, 2016* -
## Spherical Trigonometery

I am trying to apply the formula cos c = cos a x cos b + sin a x sin b x cos C to find the length of c in my spherical triangle. I am working with 2 examples in a book in which the answers are given. In the first example all the sines & cosines calculated

*asked by Mike on January 15, 2008* -
## trig

2. Determine the amplitude of: y= cos x 3. Determine the domain of: y= 4 sin x 4. Determine the range of: y= - sin x 5. Determine the period of: y= 3 sin ðx 6. Determine the phase shift of: y= 3 cos (2x -1) 7. Solve the following equation for indicated

*asked by Bernice on December 17, 2009* -
## Instantaneous rate of change

Please help.. Joe is investigating the rate of change of the function y=cos x on the interval xE[0,2π]. He notices that the graph of y=cos x passes through the x-axis at 45°. He also determines the instantaneous rate of change at x = 0, π, and 2π by

*asked by Kjd on May 23, 2012* -
## Trig

Half angle identities Find exact values of a) cos 1/2 b) sin 1/2 c) tan 1/2 based on: cos = 1/5 greater than 270 deg less than 360 deg. I get a) - rt 3/5 b) rt24/5 and c) does not work out at all .... Help please.. book says for answers a)-rt15/5 b) rt10/5

*asked by Don on January 1, 2012* -
## Pre Calculus.

Can someone check my answers please!!! Simplify (tan ^2 theta csc^2 theta-1)/(tan^2 theta). My answer: 1 Simplify ((cos x)/(sec x-1)) + ((cos x) /(sec x +1) My answer: 2cot^2 x Find a numerical value of one trigonometric function of x if (tan x/cot x )–

*asked by Austin on April 21, 2009* -
## Math

Derive this identity from the sum and difference formulas for cosine: sinasinb=1/2[cos(a-b)cos(a+b)] Start with the right-hand side since it is more complex. Calculations: _____ _____ _____ Reason: _____ _____ _____

*asked by Don'tknowtrig on May 28, 2018* -
## Trig

assume A= alpha using complementary rule how do I solve for alpha? cos(2A+40) =sin(3A-60) I don't understand how to start the question. What are the steps in solving for alpha. Do i get cos to equal sin somehow?

*asked by ALISON on September 1, 2011* -
## Calculus

Use a graphing utility to graph the polar equation shown below. r = cos 5Θ + n cos Θ, 0 ≤ Θ ≤ π For the integers n = -5 to n = 5. As you graph these equations, you should see the graph change shape from a heart to a bell. I'm sorry. I'm having

*asked by Iris on December 6, 2016* -
## Calculus

How would I find the antiderivative of this equation? S 0 to pi/3 (1-secxtans)dx This should be one that you should just recognize from your study of trig derivatives. Isn't the derivative of sec x, or (cos x)^-1 -(cos x)^-2(-sin x) ?? and isn't that

*asked by Anonymous on May 16, 2007* -
## Extrema-Check my work please?

Find and classify the relative maxima and minima of f(x) if f(x)= defint a=0 b=x function= t^2-4/(1+cos(x)^2) dt x^2-4/(1+cos(x)^2)= 0 x^2-4=0 x^2=4 x= +/- 2 So I got relative maximum as -2 and 2. And relative minimum as zero. However, when I graph it on

*asked by Eric on May 17, 2013* -
## pre cal

Suppose cos(u)=3/5 and sin(u) is positive. sin(u)= sin(u−π)= cos(u−π)= sin(u−π/2)= cos(u−π/2)=

*asked by tor on August 2, 2016* -
## 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* -
## Calculus

f(x) = 6(cos(x))^2 - 12sin(x) 0 ¡Ü x ¡Ü 2(PI) I have to find where the interval is increasing, decreasing, local mins and maxs, inflection points, and concave up and down. I understand how to do these type of problems. I am just getting messed up with

*asked by Calculus on October 11, 2010* -
## Algebra 2

Simplify the trigonometric expression. sin^2 theta / 1-cos theta A. 1+cos theta B. sin theta C. 1-sin theta / cos theta D. 1+sin theta / cos theta

*asked by Caleb on May 25, 2014* -
## Math/trig

Solve the equation in the given Domain: 1-cos theta/ sin theta = sqr3, 0degrees

*asked by Dre on November 13, 2011* -
## Pre calc

Find sin(2x), cos(2x), and tan(2x) from the given information. sin(x) = 5/13, x in Quadrant I sin(2x)? cos(2x)? tan(2x)? I honeslty just need one good example of how to do these please show all work and finalize answer

*asked by Armani on April 13, 2017* -
## physics

A 56-kg rollerblader skates across a skating rink floor. The graph below shows the net external force component F cos è along the displacement as a function of the magnitude of the displacement d. Determine the Following: (a) work done by the net force

*asked by John on October 12, 2015* -
## Math

Solve each equation for all real values of x. 7.) 3 cos 2x - 5 cos x = 1 8.) 2 sin^2 x-5 sin x + 2 = 0 9.)3 sec^2 - 4 = 0 10.) tan x (tan x-1) = 0

*asked by Maurice on March 22, 2012* -
## math

Without using a calculator, choose (a) the larger of cos 40 and cos 50; (b) the larger of sin 40 and sin 50. Be prepared to explain your reasoning.

*asked by Grace on February 8, 2017* -
## math-precalculus

sin(6x)cos(11x)+cos(6x)sin(11x)=-0.1 solve for all solutions and provide steps so I can follow.. thank you

*asked by Anonymous on May 24, 2017* -
## Pre-Calc

Evaluate the two trigonometric functions using its period as an aid. 1. cos (9pi/2) = ? Ans: 0 2. cos (-9pi/2) = ? Ans: 0

*asked by Anonymous on September 9, 2015* -
## Math!!!

angle x is in the second quadrant and angel y is in the first quadrant and angle y is in the first quardrant such that sin x=5/13 and cos y = 3/5. Determine and exact value for cos x.

*asked by Anonymous on November 8, 2010* -
## math

show that : cos(360*+x)-tan(180*-x)sin(360*-2x)cos(-x) divided by sin(90*+x)=cos2x

*asked by Ben on April 16, 2015* -
## [Calculus] U-substitution for Integrals

Integral of cos(x)*a^sin(x) + C dx = Integral of cos(x)*sin(x)^a + C dx = Let a be a fixed positive number. I'm clueless is to how to solve for a...

*asked by Ian on February 23, 2015* -
## Math/calculus

Prove Sin 8theta -sin 10theta= cot 9theta (cos 10theta - cos 8 theta)

*asked by Jessica on November 14, 2017* -
## Trigonometry

Need help solving problems using the Trigonometric Identities: 8cos^4 thet=cos4theta+4cos2theta+3 I am a bit unsure how to solve it. I am aware that the first step I must take is to simplify the problem and then use the Product to Sum formula Nasty one!

*asked by sierra on April 23, 2007* -
## Trigonometry

What is sin(cos^-1 a) when 0 < cos^-1 a < 90

*asked by Rachel on December 1, 2012* -
## Math

Simplify cos(x+y)-cos(x-y)

*asked by Jenny on December 13, 2016* -
## Trig

cos[(tan^-1(3/4))+(cos^-1(9/41))]

*asked by Hannah on May 6, 2013* -
## Algebra 2/ Trigonometry

If cos y = -4/5 when 90°≤ y ≤ 180° what is the value of cos 2y?

*asked by Moe on April 27, 2013* -
## trig

simplify cos(30+x)+cos(30-x)

*asked by Anonymous on December 11, 2010* -
## trig

Solve the following for x, where 0 < x < 2 pi. 2 cos^2 x + cos x = 1

*asked by Sandy on March 8, 2010* -
## Math

3 cos (ωt + 2) + 4 sin (ωt + 1) as A cos (ωt + φ) . A = ? φ= ?

*asked by jiya on February 2, 2016* -
## maths

cos(a+b)=m(cos(a-b) then tan a=?

*asked by pooja on April 30, 2011*