Question

If a normal chord of y²=4x makes an angle of 45^o with the axis of parabola, then its length is

• A. 8
• B. 8 $\sqrt { 2 }$
• C. 4
• D. 4 $\sqrt { 2 }$

Answer 1

Answer: (B)

8 $\sqrt { 2 }$

Answer 2

The length of the normal chord at ‘t’ = 4a.

Slope of normal at ‘t’ = -t = tan45⁰ = 1

∴ t = -1

∴ Required length of normal chord = 4. $\frac { ( 1 + 1 ) ^ { 3 / 2 } } { 1 ^ { 2 } } = 8 \sqrt { 2 }$