Question

How do you verify the identity `cos(60+A)=sin(30-A)`?

Answer 1

Please see below.

Explanation:

As `cos(90^@-theta)=sintheta`

we can write `cos(60^@+A)=cos(90^@-30^@+A)`

= `cos(90^@-(30^@-A))`

= `sin(30^@-A)`