Question

The equation of the common tangent touching the circle

(x – 3)² + y² = 9 and the parabola y² = 4x above the x-axis is –

• A. $\sqrt{3}$y = 3x + 1
• B. $\sqrt{3}$y = –(x + 3)
• C. $\sqrt{3}$y = x + 3
• D. $\sqrt{3}$y = – (3x + 1)

Answer 1

Answer: (C)

$\sqrt{3}$y = x + 3

Answer 2

(x – 3)² + y² = 9 ....(1)

̃ C₁(3, 0); r₁ = 3

y² = 4x ...(2) ̃ 4a = 4 ̃ a = 1

equation of tangent of parabola (2) is

̃ y = mx + a/m ̃ y = mx + 1/m

̃ m²x – my + 1 = 0 ...(3)

̃ C₁N = r₁ ̃ m = ? put in (3)