Question
Question: If the angles A, B, C of a triangle ABC are in arithmetical progression then...
If the angles A, B, C of a triangle ABC are in arithmetical
progression then
A
tanA+tanC−3tanAtanC=3
B
tanA+tanC+3tanAtanC=3
C
tanA+tanC−3tanAtanC=−3
D
tanA+tanC+3tanAtanC=−3
Answer
tanA+tanC+3tanAtanC=−3
Explanation
Solution
Since A, B, C are in Arithmetical progression
2B=A+C also A + B +C = 1800 so that B = 600
In a triangle ABC, we know
TanA + tanB + tanC = tanAtanBtanC
⇒ tanA+tanC = 3 (tanAtanC-(1)
⇒ tanA+tanC -3tanAtanC = −3