Question

Rewrite with only sin x and cos x.

sin 2x - cos 2x

Answer 1

sin2x = 2sinxcosx
cos2x = cos^2x-sin^2x = (cosx - sinx)(cosx + sinx)

Answer 2

Ok... I'm confused as to what comes next? 2sinxcosx-(cosx-sinx)(cosx+sinx) ?

Answer 3

@findme

Answer 4

doesn't that answer your question (rewrite the expression with only sinx and cosx)?

Answer 5

My answer choices are

2 sin2x - 2 sin x cos x + 1

2 sin x

2 sin2x + 2 sin x cos x - 1

2 sin2x - 2 sin x cos x - 1

Answer 6

2 sin^2x - 2 sin x cos x + 1

2 sin x

2 sin^2x + 2 sin x cos x - 1

2 sin^2x - 2 sin x cos x - 1

Answer 7

cos2x = 1 - 2sin^2x
how about now? can you figure it out?

Answer 8

No :(

Answer 9

sin2x = 2sinxcosx
cos2x = 1 - 2sin^2x

so, substituting the above for the given expression:
sin2x - cos2x = 2sinxcosx - (1 - 2sin^2x) = 2sin^2x + 2sinxcosx - 1

Answer 10

Thank you!

Answer 11

np