If P(h,k) be a point on the parabola x=4y2, which is nearest to the point Q(0,33), then the distance of P from the directrix of the parabola y2=4(x+y) is equal to:
Explanation
Solution
Parabola x=4y2⟹y2=41x. Point P is (4k2,k).
Distance PQ minimize karne ke liye normal P se Q(0,33) pass honi chahiye.
Normal equation at k: y−k=−8k(x−4k2).
Pass through (0,33): 33−k=−8k(0−4k2)⟹33−k=32k3⟹32k3+k−33=0
Solving gives k=1. So, P=(4,1).
Second parabola: y2−4y=4x⟹(y−2)2=4(x+1).
Iski directrix: X=−A⟹x+1=−1⟹x=−2.
Distance of P(4,1) from x+2=0 is ∣4+2∣=6.
Correct Option: (2)
Explanation
Solution
Parabola x=4y2⟹y2=41x. Point P is (4k2,k).
Distance PQ minimize karne ke liye normal P se Q(0,33) pass honi chahiye.
Normal equation at k: y−k=−8k(x−4k2).
Pass through (0,33): 33−k=−8k(0−4k2)⟹33−k=32k3⟹32k3+k−33=0
Solving gives k=1. So, P=(4,1).
Second parabola: y2−4y=4x⟹(y−2)2=4(x+1).
Iski directrix: X=−A⟹x+1=−1⟹x=−2.
Distance of P(4,1) from x+2=0 is ∣4+2∣=6.
Correct Option: (2)