We know that,cos 2θ = 1 - 2 sin2θTake θ = 30°Now, cos 60° = 1 - 2 sin230°⇒12 = 1 - 2 sin230°⇒ 2 sin230° = 12⇒sin230° = 14⇒sin 30° = 12

Question 151.

We know that, \cos 2 θ = 1 - 2 \sin^{2} θ Take θ = 30 ° Now, \cos 60 ° = 1 - 2 \sin^{2} 30 ° \Rightarrow \frac{1}{2} = 1 - 2 \sin^{2} 30 ° \Rightarrow 2 \sin^{2} 30 ° = \frac{1}{2} \Rightarrow \sin^{2} 30 ° = \frac{1}{4} \Rightarrow \sin 30 ° = \frac{1}{2}