NTA Abhyas JEE Main2020MathematicsInverse Trigonometric FunctionsPractice
If x , y , z are in arithmetic progression and tan - 1 x , tan - 1 y and tan - 1 z are also in arithmetic progression, then
Options
- Ax = y = z
- Bx = y = - z
- Cx = 1 , y = 2 , z = 3
- Dx = 2 , y = 4 , z = 6
Correct answer
A. x = y = z
Step-by-step solution
Since, x , y , z are in AP ∴ y = x + z 2 ....(i) And tan - 1 x , tan - 1 y and tan - 1 z are also in AP. ∴ 2 tan - 1 y = tan - 1 x + tan - 1 z ⇒ tan - 1 2 y 1 - y 2 = tan - 1 x + z 1 - x z ⇒ 2 y 1 - y 2 = 2 y 1 - x z [from equation. (i)] ⇒ y 2 = x z ⇒ x , y , z are in GP. ∴ x = y = z