Question

If $\sin \alpha =\frac{1}{2}$ and $\cos \beta =\frac{1}{2}$, then $(\alpha +\beta )=..........$

• A. $0^{\circ }$
• B. ${30}^{\circ }$
• C. ${60}^{\circ }$
• D. ${90}^{\circ }$

Answer 1

Answer: (D)

${90}^{\circ }$

$\sin \alpha =\frac{1}{2}\Rightarrow \sin \alpha =\sin {30}^{\circ }\Rightarrow \alpha ={30}^{\circ }$

$\cos \beta =\frac{1}{2}\Rightarrow \cos \beta =\cos {60}^{\circ }\Rightarrow \beta ={60}^{\circ }$

So, $(\alpha +\beta )={60}^o+{30}^o={90}^o$

Therefore, Answer is ${90}^o$