Question

sin 50°+ sin10°= cos20°​

Answer 1

SOLUTION

Since, sin A + sin B = 2 sin[(A+B)/2]cos[(A-B)/2]

So, sin 50°+ sin 10° = 2sin[(50°+10°)/2]cos[(50°-10°)/2]

=) 2sin( 60°/2) cos(40°/2)

=) 2 sin 30° cos 20°

=) 2× 1/2 × cos20°

=) cos 20° [Hence proved]

hope it helps ☺️