Question

Write the value of sin A cos (90° − A) + cos A sin (90° − A).

Answer 1

We have, 

`sin A cos(90°-A)=sin A sin A+cos A cos A` 

                     = `sin^2 A+cos ^2 A` 

We know that,  `sin^2 A+cos ^2 A` 

Therefore, 

\[\sin A\cos\left( 90°- A \right) + \cos A\sin\left( 90°- A \right) = 1\]