已知sin ^2 2a+sin 2acos 2a-cos 2a=1,a∈(0,2/π)求tan a

已知sin(a)=2sin(b)求sin(a/2)/sin(b/2)的值. 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 已知3SIN^2A+2SIN^2B=5SINA,求SIN^2A+SIN^2B范围 【证明】Sin A+sin B=2Sin 22 sin(arccos(2sin(a)))= 已知sin a-cos a=2sin a*cos a,则sin 2a的值怎么求? 已知sin a+cos a= -1/5 求1）sin acos a 2）sin a-cos a 若sin^2a sin^2(-a)化简 已知tana=2,则[sin(π/2+a)-cos(π-a)]/[sin(π/2-a)-sin(π-a)]=? 已知tan a=2,求sin a+cos a /cos a -sin a 的值 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 已知sin(3π+a)=2sin[(3π/2)+a],求sin^2a+sin2a的值 已知sin(3π+a)=2sin(3π/2+a),sin^2a+sin2a = sin a+sin 2a +sin 3a +...+sin na怎么求和? sin a+sin 2a +sin 3a +...+sin na怎么求和? 已知 sin a-cos a=1/2,则 sin^3 a-cos^3 a