Question

in triangle ABC, find the value of tan A + tan b + tan C is equal to​

Answer 1

A + B + C = 180

A + B = 180 - C

Multiplying by tan both sides ;

tan ( A + B ) = tan ( 180 - C )

Applying tan ( A + B ) and tan ( 180 - θ ) ;

$\frac{tanA +tanB}{1-tanA.tanB}=-tanC$

Cross - multiplying ;

tanA + tanB = -tanC + tanA.tanB.tanC

tanA + tanB + tanC = tanA.tanB.tanC

Hope it helps u ....  :D