Question

Plz anyone solve this question........​

Answer 1

Step-by-step explanation:

We know : Cos ( 90° - θ ) = Sin θ

So, Cos 18° = Cos ( 90° - 72° ) = Sin 72° , Substitute that value in ( Sin 72° + Cos 18° ) ( Sin 72° - Cos 18° ) and get

= ( Sin 72° + Sin 72° ) ( Sin 72° - Sin 72° )

= ( 2 Sin 72° ) ( 0 )

= 0

sorry second one I can't give you

hope first one helps you!!!!