ABC is a triangle If $$sin(\frac{A+B}{2})=\frac{\sqrt{3}}{2}$$, then the value of $$sin\frac{C}{2}$$ is
In $$\triangle$$ ABC, $$\angle$$ A +Â $$\angle$$Â B +Â $$\angle$$Â C = $$180^\circ$$
=> $$\angle A + \angle B = 180^\circ - \angle C$$
Dividing both sides by '2',
=> $$\frac{A+B}{2}=90^\circ-\frac{C}{2}$$ ----------(i)
Given : $$sin(\frac{A+B}{2})=\frac{\sqrt{3}}{2}$$
Substituting value from equation (i), we get :
=> $$sin(90^\circ-\frac{C}{2})=\frac{\sqrt{3}}{2}$$
Using, $$sin(90^\circ-\theta)=cos\theta$$
=>Â $$cos(\frac{C}{2})=\frac{\sqrt{3}}{2}$$
=> $$\frac{C}{2}=cos^{-1}(\frac{\sqrt{3}}{2})$$
=> $$\frac{C}{2}=30^\circ$$
=> $$\angle C = 30 \times 2 = 60^\circ$$
$$\therefore$$Â $$sin\frac{C}{2}$$ = $$sin(\frac{60}{2})$$
= $$sin(30^\circ)=\frac{1}{2}$$
=> Ans - (C)
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