(sinA)^2=(sinB)^2+(sinC)^2+sinAsinB,求A

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(sinA)^2=(sinB)^2+(sinC)^2+sinAsinB,求A(sinA)^2=(sinB)^2+(sinC)^2+sinAsinB,求A(sinA)^2=(sinB)^2+(sinC)

(sinA)^2=(sinB)^2+(sinC)^2+sinAsinB,求A
(sinA)^2=(sinB)^2+(sinC)^2+sinAsinB,求A

(sinA)^2=(sinB)^2+(sinC)^2+sinAsinB,求A
题目不完整应该是在△ABC内将角化为边 a^2=b^2+c^2+ab 变形后b^2+c^2-a^2=-ab 用余弦定理 COSA=-1/2 A=120°

三角形abc sina sinb sinc 成等差数列 tanc=2根号2求sinb/sina 求c=11面积s 求证三角形面积公式S=1/2a^2(sinB×sinC)/sinA 求证三角形面积公式S=1/2a^2(sinB×sinC)/sinA 求证:sina^2+sinb^2-sina^2*sinb^2+cosa^2*cosb^2=1 sina^2+sinb^2+1/4=sinasinb+1/2(sina+sinb) (1+sina-cosa)/sina * (1+sinb-cosb) /sinb=2,求tana*tanba,b是锐角. 若3sina^2+2sinb^2=2sina,求sina^2+sinb^2的取值范围? 已知3sina平方+2sinb平方=2sina ,求sina平方+sinb平方的取值范围? 在△ABC中,求证sinA平方+sinB平方-sinC平方=2sinAsinBcosC(2)sinA+sinB-sinC=4sinA/2sinB/2cosC/2 已知三角形ABC,(sinA+sinB)(sinA-sinB)=sinC(根号2sinA-sinC)1.求角B 2.若sinA=3/5,求cosC的值 (sinA)^2=(sinB)^2+(sinC)^2+sinAsinB,求A SinA=2SinB TanA=3TanB CosA=? sinA+√2sinB=2sinC,求cosC最小值为什么sina^2+sinb^2=1.前提是什么 sina+2sinb,tana=3tanb,则cosa= 已知sina=2sinb.tana=3tanb,cosa tanA=3,tanB=2,如何求sinA,sinB?) sina+cosa=1/2,sinb-cosb=1/3