Question

Simplify the expression by using a double-angle formula 1-2sin^2(3theta)

Answer 1

We know that:


`\cos(2x)=1-2\sin^2(x)`

Here
`x=3\theta` so:


`1-2\sin^2(3\theta)=\cos(2\cdot3\theta)=\cos(6\theta)`