Question

Prove the identity. cos^2x-sin^2x-1=1-2sin^2x

Answer 1

something is wrong here..

Answer 2

are you sure that this is the question?

Answer 3

yes but we were thought to use theta in the place of x. there is not sign for it on my computer

Answer 4

no this is not the problem here.. there is something wrong in the question
it isnt right lol

Answer 5

check if you copied it right

Answer 6

oh lol this is what the problem shows here. cos squared x-sin squared x=1-2sin squared x.

Answer 7

i wrote it out to see it that helps but that is how it is written.

Answer 8

oh now its fine.. you see you wrote in the first place an extra -1 on the left side

so:
using cos^2x + sin^2x = 1
we get
cos^2x = 1-sin^2x
plug it into your equation
1-sin^2x -sin^2x = 1 -2sin^2x
1-2sin^2x = 1-2sin^2x
done

Answer 9

thank you