## anonymous 3 years ago Verify the identity. sin (4u) = 2 sin (2u) cos (2u) Please help, verifying these kind of equations is tricky for me.

1. slaaibak

Hmm. you can try doing it like this: sin(2u + 2u) = sin(2u) * cos(2u) + cos(2u) * sin(2u) = 2sin(2u)*cos(2u) Note: I referred to: sin(A + B) = sinAcosB + cosAsinB

2. anonymous

Oh, I see. Is that the final answer?

3. anonymous

I mean, is that it? Usually these questions take up more space. >_<

4. slaaibak

I'm pretty sure it is, yes

5. AravindG

you can also use the identity that $\bf \large \boxed{\sin 2A= 2\sin A \times \cos A }$

6. AravindG

treating $4u=2 \times (2u)$