Question

Which if the following is a consequence of the identity sin 2x=2(sin x)(cos x ) ?

A. sin y = (sin 1/2y)
B. sin 3y= 3( sin 2y)(cos y)
C. sin 4y= 2( sin 2y) ( cos 2y)
D. sin 4y= 4 ( sin 2y) ( cos 2y)
E. sin 8y= 2 ( sin 4y) (cos 2y)

Answer 1

`sin2x=2sinxcosx\\\\Answer:C.\ sin4y=2sin2ycos2y\\\\because:\\\\sin4y=sin[2(2y)]=2sin2ycos2y`