Question

22. If sine + sin 20 + sin30 = sina and cose + cos20 + cos30 = cosa, then is equal to o la (3) 20

JEE/Engineering Exams

Maths

Solution

138

4.0 (2 ratings)

( sin theta+sin 2 theta+sin 3 theta=sin alpha ) ( frac{2 sin 2 theta cos theta+sin 2 theta=sin alpha}{alpha operatorname{cin} 2 theta(2 cos theta+1)=sin alpha} mid frac{cos theta+cos 2 theta+cos 3 theta=cos alpha}{2 cos 2 theta cos theta+cos 2 theta=cos alpha} ) [ C ] ¿iniding 12 ( tan 2 theta=tan alpha ) ( 2 theta=infty cdot 2 ) ( T theta=frac{alpha}{2} )