Maths-
General
Easy
Question
If normal at point P on parabola y2 = 4ax, (a > 0) meet it again at Q is such a way that OQ is of minimum length where O is vertex of parabola, then ΔOPQ is
- a right angled triangle
- obtuse angled triangle
- acute angled triangle
- None
The correct answer is: a right angled triangle
Normal at P(t1) meets at Q(t2)
t2 = 
For minimum length of OQ, |t2| should be minimum
i.e. | t2 | = 
If t2 = 
t1 = 
Slope of OQ = 
= m1 and of OQ = 
= m2
m1m2 = –1 
OPQ is right angled triangle.
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