Question

If $\sin \theta =\frac{1}{2}$ and $0^{\circ }<\theta <{90}^{\circ }$ then $\cos 2\theta =$ _____

• A. $0$
• B. $1$
• C. $\frac{1}{2}$
• D. $\frac{\sqrt{3}}{2}$

Answer 1

The correct option is C $\frac{1}{2}$

Given, $\sin \theta =\frac{1}{2}$
$=>\theta ={30}^0$ (Since, $\sin {30}^0=\frac{1}{2}$ and $0^0<\theta <{90}^0)$
So, $\cos 2\theta =\cos \left({60}^0\right)=\frac{1}{2}$