1.若sin(a+β)=1/2,sin(a-β)=1/3,则tana/tanβ为?2.sinxcosy=1/2,则sinycosx的取值范围是?

1-sin a+sin a的平方-sin a的立方+……若a是正锐角,且sin a-cos a=0.5,求1-sin a+sin^2a-sin^3a+…… 求证1+sin a+cos a+2sin acos a/1+sin a+cos a=sin a+cos a 懂得进.证明,sina+sin(a+b)+sin(a+2b)+...sin(a+nb)=sin(a+ab/2)sin[(n+1)b/2]/sin(b/2) 若sin^2β-sin^2α=m,则sin(α+β)sin(α-β) sin 2a+2sin方a/ 1+tan a =2sin a cos a 求证:sin 2a/1+sin a+cos a=sin a+cos a-1急 cosA+cos^2A=1,sin^2A+sin^4A+sin^8A 在△ABC中,求证；sin^(A/2)+sin^(B/2)+sin^(C/2)=1-2sin(A/2)sin(B/2)sin(C/2） 证明 sin^2A+sin^2B-sin^2A*sin^2B+cos^2A*cos^2证明 sin^2A+sin^2B-sin^2A*sin^2B+cos^2A*cos^2B=1 sin^2a+sin^2β-sin^2a*sin^2β+cos^2a*cos^2β=1 证明恒等式?各位高手 教教我 【证明】Sin A+sin B=2Sin 22 sin(arccos(2sin(a)))= 若3sin²a+sin²β=2sina,求2sina+sin²β sin阝=1/3,sin(a+阝)=1,求sin(2a+3阝) 若tanβ=a(a>1),求[sin(派/4+β)]/[sin(派/2-β)]*tan2β的值 若sin^4a/sin^2b+cos^4a/cos^2b=1,证明sin^4b/sin^2a+cos^4b/cos^2a=1.(不用向量怎么证?) 若sin^2a 以知cos(a+β )=-1,求证sin(2a+β )+sinβ=0