◆◆◆求证sin^2a+sin^2β-sin^a*sin^2β+cos^2a*cos^2β=1最好步骤简洁,能够让人明白,禁止抄袭!应是sin^2a+sin^2β-sin^2a*sin^2β+cos^2a*cos^2β=1

◆◆◆求证sin^2a+sin^2β-sin^a*sin^2β+cos^2a*cos^2β=1最好步骤简洁,能够让人明白,禁止抄袭!应是sin^2a+sin^2β-sin^2a*sin^2β+cos^2a*cos^2β=1 求证:sin(a+b)sin(a-b)=sin^2a-sin^2b 求证数学题,在三角形ABC中,求证sin^2(A)+sin^2(B)+sin^2(C) 求证:sin(2α+β)/sinα-2cos(α+β)=sinβ/sinα 求证sin(2α+β)/sinα-2cos(α+β)=sinβ/sinα 求证sin(2α+β)/sinα-2cos(α+β)=sinβ/sinα 求证sin(2α+β)/sinα-2cos(α+β)=sinβ/sinα 求证:sin 2a/1+sin a+cos a=sin a+cos a-1急 求证1+sin a+cos a+2sin acos a/1+sin a+cos a=sin a+cos a 求证:sin(a+β)sin(a-β）=（cosβ）^2-(cosa)^2 以知cos(a+β )=-1,求证sin(2a+β )+sinβ=0 求证：sin²α+sin²β+2sinαsinβcos(α+β)=sin²(α+β) 在△ABC中,求证；sin^(A/2)+sin^(B/2)+sin^(C/2)=1-2sin(A/2)sin(B/2)sin(C/2） sin^2A+sin^2B=sin^2C求证△ABC的形状 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 求证：sinα+sinβ=2sin(α+β)/2 *cos（α-β）/2 求证sinα-sinβ=2cos(α+β)/2sin(α-β)/2 求证 sinαcosβ=1/2[sin(α+β)+sin(α-β)]