Correct Answer - Option 2 : 1/2
Concept:
- sin (A + B) = sin A cos B + cos A sin B
- sin (A - B) = sin A cos B - cos A sin B
Calculation:
We know that , sin A cos B - cos A sin B = sin (A - B)
putting , A = 40° and B = 10° in the above identity, we get
sin 40° cos 10° - cos 40° sin 10°
= sin (40° - 10°)
= sin 30°
= 1/2.
The correct option is 2.
