Question

The value of $sin\theta .cos({90}^{\circ }-\theta )+cos\theta .sin({90}^{\circ }-\theta )$ is

• A. $1$
• B. $0$
• C. $2$
• D. $-1$

Answer 1

The correct option is A $1$

$\sin \theta .\cos (90°-\theta )+\cos \theta \sin (90°-\theta )$

$=\sin \theta .\sin \theta +\cos \theta \cos \theta$

$={\sin }^2\theta +{\cos }^2\theta$

$=1$