Question
Mathematics Question on Ellipse
The line x=8 is the directrix of the ellipse E:a2x2+b2y2=1 with the corresponding focus (2,0) If the tangent to E at the point P in the first quadrant passes through the point (0,43) and intersects the x-axis at Q, then (3PQ)2 is equal to ____
Answer
The correct answer is 39
ea=8....(1)
ae =2....(2)
8e=e2
e2=41⇒e=21
a=4
b2=a2(1−e2)
=16(43)=12
4xcosθ+23ysinθ=1
sinθ=21
θ=30∘
P(23,3)
Q(38,0)
(3PQ)2=39