Question

If `sinx=2/4`, how do you find `cos2x`?

Answer 1

`cos2x=1/2`

Explanation:

We have the identity `cos2x=1-2sin^2x`

Hence as `sinx=2/4`,

`cos2x=1-2sin^2x=1-2(2/4)^2`

= `1-(2xx2xx2)/(4xx4)`

= `1-1/2=1/2`