# Math

Prove the identity cos3x ≡ 4cos^3x - 3cosx

Thank you so much for the help!

1. 👍 0
2. 👎 0
3. 👁 68
1. Just noticed that this question has been answered before

1. 👍 0
2. 👎 0
posted by Autumn

## Similar Questions

1. ### trig

By expressing 3x as (2x + x) prove that cos3x = 4cos^3x - 3cosx

asked by Rin on December 13, 2011
2. ### trig

By expressing 3x as (2x + x) prove that cos3x = 4cos^3x - 3cosx

asked by Rin on December 13, 2011
3. ### precalc

prove the identity : cos3x =4 cos^3x-3cosx

asked by Anonymous on March 6, 2018
4. ### maths...

Differentiate ln [x+√(x^2+1)] with respect to x hence evaluate limit 0 to 1 ∫ 1/√(x^2+1) dx _________________________________________ Use the identity cos3x=4cos^3x-3cosx, find ∫cos^3x dx * Is there a printing error in the

asked by Aoi on June 19, 2009
5. ### maths

find the value of x if sin2x+3cosx=2 then cos3x+sec3x is

asked by rajagopal on September 6, 2017
6. ### trig

how do you verify cos3x=4cos^3x-cosx???

asked by lindsey edler on July 12, 2005
7. ### math

Prove the identity: cos^4(x)-sin^4(x)=1-2sin^2(x).with explanation im confused on this one cause of the 4th power of the sine. does this mean that we put it in the calculator 4 times? and what exactly does it mean by prove the

asked by Anonymous on April 15, 2012
8. ### pre-cal

find all solutions in interval [0,2pi] tan²x = -3/2 secx This question may look tricky, but its actually quite simple. First: rearrange the pythagorean identity tan²x+1=sin²x so that it reads tan²x=sin²x-1 Then replace the

asked by ethan on May 16, 2007
9. ### Trig

verify the following identity: 2sinxcos^3x+2sin^3cosx=sin(2x)

asked by Lynn on July 19, 2012
10. ### Trigonometry

Verify Identity: cos5x-cos3x=-8sin^2x(2cos^3x-cosx)

asked by Erik on July 2, 2011

More Similar Questions