Question

How do you use double angle identities to solve equations?

Answer 1

As below.

Explanation:

Following table gives the double angle identities which can be used while solving the equations.

You can also have `sin 2theta, cos 2theta` expressed in terms of `tan theta` as under.

`sin 2theta = (2tan theta) / (1 + tan^2 theta)`

`cos 2theta = (1 - tan^2 theta) / (1 + tan^2 theta)`