Maths-
General
Easy
Question
The length of a focal chord of the parabola y2 = 4ax at a distance b from the vertex is c. Then
- 2a2 = bc
- a3 = b2c
- ac = b2
- b2c = 4a3
The correct answer is: b2c = 4a3
Chord joining two points t1 and t2 is
(t1 + t2)y = 2x + 2at1t2
= b... (1)
a (t1 – t2)2 = c ... (2)
By using (1) and (2), eliminate t1 & t2
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