Question

how to calculate values like sin 50 cos 120 ?

Answer 1

$$\begin{gathered} \mathrm{I}\mathrm{assume}\mathrm{it}\mathrm{should}\mathrm{be}\sin 150°\mathrm{instead}\mathrm{of}\sin 50°. \\ \sin 150°=\sin \left(90°+60°\right)=\cos 60°=\frac{1}{2}\left[\mathrm{as},\sin \left(90°+\mathrm{\theta }\right)=\cos \mathrm{\theta }\right] \\ \cos 120°=\cos \left(180°-60°\right)=-\cos 60°=-\frac{1}{2}\left[\mathrm{as},\cos \left(180°-\mathrm{\theta }\right)=-\cos \mathrm{\theta }\right] \end{gathered}$$