梦幻龙族2祭司加点:sinA+sin5A+sin9A=sin3A+sin7A

sinA+sin5A+sin9A=sin3A+sin7A 已知：sinA+sin^2A=1 求sin^2+sin^4的值 sina=x sinb=y sin(a+b)=? 证明sin3a=3sina-4sin立方a 证明sin3a=3sina-4sin立方a 证明sin3a=3sina-4sin立方a sina+cosa/sina-cosa = 2 则sin(a-5pai)sin(3pai/2 - a)=?? 已知3sin^A+2sin^B=2sinA 求cos^A+cos^B的最值 为什么sina+sinb==2sin(a+b)/2*cos(a-b)/2 cos(a+b)=0求证sin(a+2b)=sina