Question: sin 2a is equal to?
Answer: How to proof the formula of sin 2A is equals 2 sin A cos A? Note: In the above formula we should note that the angle on the R.H.S. is half of the angle on L.H.S. Therefore, sin 60° = 2 sin 30° cos 30°. The above formula is also known as double angle formulae for sin 2A.