Help please!
sin4x=3cos^3xsinx-4sin^3xcosx
2 answers
I'm not sure if this is a half angle identity because the cubes throw me off
simplify the left side into x's
sin 4x
= 2sin 2x cos 2x
= 4sinx cosx(cos^2x - sin^2x)
= 4cos^3 x sinx - 4sin^2 x cosx
= almost the right side
I suspect a typo
sin 4x
= 2sin 2x cos 2x
= 4sinx cosx(cos^2x - sin^2x)
= 4cos^3 x sinx - 4sin^2 x cosx
= almost the right side
I suspect a typo
2 answers