tan(A+B)=(tanA+tanB)/(1-tanAtanB)
tan(A+B)(1- tanAtanB)=tanA+tanB=根号3tanAtanB-根号3
tan(A+B)= -根号3,tan(180度-C)=-tanC,tanC=根号3,C=60°
tan(A+B)=(tanA+tanB)/(1-tanAtanB)
tan(A+B)(1- tanAtanB)=tanA+tanB=根号3tanAtanB-根号3
tan(A+B)= -根号3,tan(180度-C)=-tanC,tanC=根号3,C=60°