Question

If b and c are the lengths of the segments of any focal chord of a parabola y² = 4ax, then the length of the semi-latus rectum is

• A. $\frac{bc}{b + c}$
• B. $\frac{2bc}{b + c}$
• C. $\frac{b + c}{2}$
• D. $\sqrt{bc}$

Answer 1

Answer: (B)

$\frac{2bc}{b + c}$

Answer 2

Since the semi latus rectum of a parabola is the harmonic mean between the segments of any focal chord of a parabola, semi latus rectum =$\frac{2bc}{b + c}$.