已知sin(a+b)sin(a-b)=-1/3,求cos^2a-cos^2b的值

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+b)sin(a-b)=sin^2 a-sin^2 b, 如何证明sin(a+b)sin(a-b)=sin*a-sin*b (*为平方) 求证恒等式sin(A+B)sin(A-B)=sin²A-sin²B 求证:sin(a+b)sin(a-b)=sin^2a-sin^2b sin a-sin b等于 已知3sin b=sin(2a+b) 求证tan(a+b)=2tana 已知 3sin A = sin (2B +A ),求证 ： tan（A+B)= 2tanB 【证明】Sin A+sin B=2Sin 22 已知sin(A+B)=2/3,sin(A-B)=1/5.求tanA/tanB 已知sin(a+b)=1/2,sin（a-b)=1/3,求tana/tanb 已知SIN A=0.6275,SIN B=0.0547,求A,B的度数 已知sinA=1/5,求2sin(A+B)cosA-sin(2A+B) 已知sin(A+B)sin(B-A)=m,则cosA的平方-cosB的平方 已知sin(a+B)sin(a-B)=1/3,求cos2b-cos2a sin(a+b)sin(a-b)=sin2a-sin2b求证