# How to prove this trigonometric identity?

##### 1 Answer

See below

#### Explanation:

Are you happy about these identities?

If so then proving identities, as above, is a matter of doing something and seeing where you get to!!!

LHS can be written

=

RHS

Multiply LHS and RHS by

LHS=

RHS=

=

=

Now looking at the LHS and remembering that

LHS=

=

We are there!!!

Difficult for me to write this really clearly here, paper would be easier!!!

BUT THE IMPORTANT THING WITH IDENTITIES IS DO SOMETHING AND YOU WILL GET THERE.