Question

Simplify parenthesis https://gyazo.com/e841c7a299e13b1771f252c34b467f37

Answer 1

\[\left( a-b \right)\left( a+b \right)=a^2-b^2\]

Answer 2

sshayer has suggested that you use the above "special product" to simplify the given trig expression.

Please apply this suggestion, sharing your work as you go.

Then, check out trig identities that involve the sine and cosine functions. Siimplify.;