Answer
Please refer to the step-by-step part below.
Work Step by Step
Use the identity $\sin{(\alpha-\beta)}=\sin{(\alpha)}\cos{(\beta)}-\cos{(\alpha)}\sin{(\beta)}$ to obtain:
$\sin{(\pi-\theta)}\\=\sin{(\pi)}\cos{(\theta)}-\sin{(\theta)}\cos{(\pi)}\\=0\cos{(\theta)}-(-1)\cdot \sin{(\theta)}\\=\sin{(\theta)}$
