Question

prove that sin2A = 2sinAcosA

Answer 1

sin(2A) = sin(A + A) 
As sin(a + b) = sinacosb + sinbcosa, 
sin(A + A) = sinAcosA + sinAcosA 
Therefore sin(2A) = 2sinAcosA

Answer 2

Step-by-step explanation:

sin2A=2sinAcosA

sin2A=sin(A+A)

sin(a+b)=sina cosb+sinb cosa

sin2A=2sinAcosA

Hence proved