cos(A+B)/cos(A-B) =cosAcosB-sinAsinB/cosAcosB+sinAsinB =1-tanAtanB/1+tanAtanB =1-3/1+3 =-2/4 =-1/2
The answer is -1/2. Tan A=Sin A/Cos A Tan B=Sin B/Cos B Tan A*Tan B= SinASinB/CosACosB=3 SinASinB=3CosACosB Cos(A+B)=CosACosB-SinASinB =CosACosB - 3CosACosB = -2CosACosB Cos(A-B)=CosACosB + SinASinB =CosACosB + 3CosACosB =4CosACosB Cos(A+B)/Cos(A-B) = -2CosACosB/4CosACosB = -1/2.
If in a triangle ABC: Cos A + Cos B + Cos C = 3/2 then what is so special about this triangle?
Try to solve this problem using substitution of only basic values of trigonometric functions(30,60,90) and post the complete solution?