JEE Main2016MathematicsApplication of DerivativesActual
Consider f x = tan - 1 ⁡ 1 + sin ⁡ x 1 - sin ⁡ x , x ∈ 0 , π 2 . A normal to y = f x at x = π 6 also passes through the point
Options
- Aπ 6 , 0
- Bπ 4 , 0
- C0 , 0
- D0 , 2 π 3
Correct answer
D. 0 , 2 π 3
Step-by-step solution
f x = tan - 1 ⁡ 1 + sin ⁡ x 1 - sin ⁡ x ,   x   ∈ 0 , π 2 f ′ ( x ) =   1 1 + 1 + sin ⁡ x 1 - sin ⁡ x   . 1 2   1 + sin ⁡ x 1 - sin ⁡ x - 1 2   .   cos ⁡ x 1 - sin ⁡ x + cos ⁡ 1 + sin ⁡ x 1 - sin ⁡ x 2 at x = π 6 f ′ x = 1 2 2   . 1 2   1 3   3 1 4 = 1 2 Slope of tangent = 1 2 So slope of normal =   - 2 Also at x = π 6 ,     y = tan - 1 ⁡ 3 =