Q.

A parabola touches the lines y= x and y=-x at P (3, 3) and Q (2,-2) respectively. Then 

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a

Equation of directrix is  x+5y=0

b

Equation of line through origin and parallel to axis is  x5y=0

c

Focus is  (3013,613)

d

Equation of line through origin and focus is  x+5y=0

answer is A, C, D.

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Detailed Solution

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 Midpoint of PQ=(52,12)  =R
Slope of OR= 15
Slope of axis =    15
(  Line joining the point of intersection of tangents at A and B on parabola and mid-point of chord AB is always parallel to axis of parabola)
  Slope of directrix = -5
Eq.of directrix:  y=-5x   5x+y=0
Circle with OP as diameter:  x2+y23x3y=0
Circle with OQ as diameter:  x2+y22x+2y=0
Focus is the point of intersection of circles:  S=(3013,613)
Eq.of line joining origin to focus is: x+5y=0

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A parabola touches the lines y= x and y=-x at P (3, 3) and Q (2,-2) respectively. Then