Question 38

If θ is acute angle and sin(θ+18°)= 1/2, then the value of θ in circular measure is

Solution

Given : $$sin(\theta+18^\circ)=\frac{1}{2}$$

=> $$sin(\theta+18^\circ)=sin(30^\circ)$$

=> $$\theta+18^\circ=30^\circ$$

=> $$\theta=30^\circ-18^\circ=12^\circ$$

Now, $$180^\circ=\pi$$ radians

=> $$12^\circ=\frac{\pi}{180} \times 12=\frac{\pi}{15}$$ radians

=> Ans - (B)

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