A,B,C是三角形ABC的三内角,向量M=(-1,根号3),向量N=(cosA,sinA)且MN=1
(1)求角,(2)若1+sin2/(cosBcosB-sinBsinB)=-3B,求tanB。
M*N=-cosA+√念咐3sinA=2sin(A-π/3)=1 sin(A-π/3)=1/2 A=π/2 (1+sin2B)/仔虚纯[(cosB)^2-(sinB)^2] =(sinB+cosB)^2/(sinB+cosB)(cosB-sinB) =(sinB+cosB)/(cosB-sinB)(分子分母同除cosB) =(tanB+1)/(1-tanB) =-3 tanB=2 追问: 能再详誉弯细么