证明:2sina+sin2a=4sina*cos^2a/2

问题描述:

证明:2sina+sin2a=4sina*cos^2a/2

2sina+sin2a=2sina*(1+cosa)=2sina*(sin^2a/2+cos^2a/2+cos^2a/2-sin^2a/2)=4sina*cos^2a/2