sin阿尔法等于多少,sin阿尔法与cos阿尔法关系

=sina/2^2+cosa/2^2 sina=2sina/2*cosa/2 1+sina =[sin(a/2)]^2+[cos(a/2)]^2+2[sin(a/2)][cos(a/2)] =[sin(a/2)+cos(a/2)]^2