JEE MainHardQuestion 400007
Question
The tangent at (a cos θ, b sin θ) to the ellipse x²/a² + y²/b² = 1 is:
- A(x cos θ)/a + (y sin θ)/b = 1Correct
- Bx cos θ/a − y sin θ/b = 1
- Cx/a + y/b = 1
- Dx cos θ + y sin θ = 1
Correct answer
(x cos θ)/a + (y sin θ)/b = 1
Explanation
Using T = 0 formula: tangent at (x₁, y₁) to ellipse: xx₁/a² + yy₁/b² = 1. At parametric point (a cos θ, b sin θ): x(a cos θ)/a² + y(b sin θ)/b² = 1 → (x cos θ)/a + (y sin θ)/b = 1.