Question

Proof: (cosx-sinx)^2=1-sin2x

Answer 1

\[(\cos x-\sin x)^2 = \cos^2 x - 2\cos x\sin x + \sin^2 x\]Just remember that \(\cos^2x+\sin^2x=1\)

So you have \(1- 2\cos x\sin x\)

\(2\cos x\sin x\) reminds me of something, like Double Angle Formulas?

Answer 2

http://www.sosmath.com/trig/Trig5/trig5/trig5.html

Answer 3

I know that sin2x=2sinxcosx

Answer 4

well so now now u have (1- sin2x) so ur proof is done

Answer 5

Ok thanks!