Question

Write the value of $\sin \theta \cos \left(90°-\theta \right)+\cos \theta \sin \left(90°-\theta \right)$.

Answer 1

$$\begin{gathered} \sin \theta \cos \left(90°-\theta \right)+\cos \theta \sin \left(90°-\theta \right) \\ =\sin \theta \sin \theta +\cos \theta \cos \theta \\ ={\sin }^2\theta +{\cos }^2\theta \\ =1 \end{gathered}$$