Question

sin 4u = 2 sin 2u cos 2u

verify the identity

Answer 1

@Mertsj @mebs

Answer 2

@satellite73

Answer 3

You have the identity sin 2x = 2sin x cos x

Answer 4

Let x = 2u
Then 2x = 4u
Make the substitutions

Answer 5

so it would be sin2x=2sinxcosx?

Answer 6

and then from there what do i have to do just solve?

Answer 7

so we have an identity \[\sin(A+B) = sinAcosB + cosAsinB\]

we have sin(4u) = sin(2u + 2u)

can you substitute and sovle?

Answer 8

to solve would just leave me with cosx rigth ?
@Mertsj @mebs

Answer 9

no it wouldn't ...

here it would look like this

sin(2u + 2u) = sin2ucos2u + sin2ucos2u

add them and you prove the identity.. its self explanatory.