Question

If b, c are intercepts of a focal chord of the parabola y² = 4ax then c is equal to

a. b/b-a

b. a/b-a

c. ab/a-b

d. ab/b-a

Answer 1

Correct option is \(\frac{ab}{b-a}=c\)

We know that \(2a=\frac{2\times SA\times SB}{SA SB}\)

2a= 2bc/b+c

⇒ ab=bc-ac

ab=(b-o)c

ab+ac = bc

\(\frac{ab}{b-a}=c\)