Multiple Angle Identity

[jessilovin]

Verify the identity using multiple-angle formulas. I am totally lost!!!!!!!

1a) cos^(2)3x-sin^(2)3x=cos6x


1b) (sin^(2)2?)/(sin^(2)?)=4-4sin^(2)?

 

[pka]

You should know: $\displaystyle \cos \left( {2\phi } \right) = \cos ^2 \left( \phi \right) - \sin ^2 \left( \phi \right) = 2\cos ^2 \left( \phi \right) - 1 = 1 - 2\sin ^2 \left( \phi \right)$

and $\displaystyle \sin \left( {2\phi } \right) = 2\sin \left( \phi \right)\cos \left( \phi \right)$