Published by:
CGP EDU Academic Team
Published on: August 13, 2026
The normal y = mx – 2am – am2 to the parabola y2 = 4ax subtends a right angle at the origin, then-
A
m = 1
B
m = 
C
m = 2
D
m = 
Text Solution
Verified by ExpertsThe correct answer is:
B
Standard equation of the normal at P(at 2 , 2at) is y + xt
= 2at + at 3 .
Hence t = – m. This meets the parabola again at Q whose parameter is – t – 
or m + 
∴ coordinates of Q are a 
, 2a 
Since ∠ POQ = 90 0 ⇒ 
= –1
⇒ m 2 + 2 = 4
⇒ m = ± 
m = 
is one of the choices.
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