JEE MainMathematicsParabola
A focal chord of the parabola y^2 - 4x - 2y + 9 = 0 is tangent to the circle x^2 + y^2 - 12x - 2y + 34 = 0 . The length of this focal chord is equal to _____ .
Correct answer
12
Step-by-step solution
The given equation of the parabola is y^2 - 4x - 2y + 9 = 0 . Completing the square, we get: y^2 - 2y + 1 = 4x - 8 (y-1)^2 = 4(x-2) Comparing with (y-k)^2 = 4a(x-h) , we have 4a = 4 a = 1 . The focus of the parabola is (h+a, k) = (3, 1) . The given equation of the circle is x^2 + y^2 - 12x - 2y + 34 = 0 . Completing the square, we get: (x-6)^2 + (y-1)^2 = 36 + 1 - 34 = 3 The center of the circle is (6, 1) and its radius is 3 . Let the slope of the focal chord be m . Since it passes through the focus (3, 1) , its eq