[3sin^2 (a/2)-2sin(a/2)cos(a/2)+cos^2 (a/2)]/[tana+1/tana]

sin a+sin 2a +sin 3a +...+sin na怎么求和? sin a+sin 2a +sin 3a +...+sin na怎么求和? 3 在三角形ABC中,已知（a2+b2）sin（A-B）=（a2-b2）sin(A+B) 求证：ABC是等腰或直角三角形(a^2+b^2)sin(A-B)=(a^2-b^2)sin(A+B),(sin^A+sin^B)sin(A-B)=(sin^A-sin^B)sin(A+B) sin^A*(sin(A+B)-sin(A-B))=sin^B*(sin(A-B)+sin(A+B)) sin^A*2c 若sin^2a sin^2(-a)化简 sin(arccos(2sin(a)))= 化简求sin^2(a-π/3)+sin^2(a+π/3)+sin^2a 化简：sin^2a+sin^2(a-180/3)+sin^2(a+180/3) 化简；sin^2 A+sin^2(A-π/3)+sin^2(A+π/3) 化简sin^2A+sin^(A-π/3)+sin(A+π/3) 【证明】Sin A+sin B=2Sin 22 证明sin(a+b)sin(a-b)=sin^2 a-sin^2 b, 求证:sin(a+b)sin(a-b)=sin^2a-sin^2b 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+…… sin阝=1/3,sin(a+阝)=1,求sin(2a+3阝) 已知3SIN^2A+2SIN^2B=5SINA,求SIN^2A+SIN^2B范围 已知sin(a)=2sin(b)求sin(a/2)/sin(b/2)的值. 求证1+sin a+cos a+2sin acos a/1+sin a+cos a=sin a+cos a