1.

Match the conditions/expression in Column I With statement in Column II. Normals at P,Q,R are drawn to y^(2) = 4x which intersect at (3,0). Then, {:("column I","column II"),(A."Area of" Delta PQR,p.2),(B. "Radius of circumcircle of" Delta PQR,q.(5)/(2)),(C. "Centroid of" Delta PQR,r. ((5)/(2),0)),(D. "Circumcentre of" Delta PQR,s. ((2)/(3),0)):}

Answer»


Solution :since, EQUATION of normal to the parabola `y^(2) = 4ax` is `y + xt = 2at + at^(3)` passes through (3,0)
`implies 3t = 2t + t^(2)`
`implies t = 0, 1 -1`
`:. ` Coordinates of the NORMALS are `P(1,2), Q(0,0) R(1,-2)`
Thus,
A. AREA of `Delta PQR = (1)/(2) XX 1 xx 4 = 2`
C. Centriod of `Delta PQR = ((2)/(3), 0)`
Equation of circle passing through P,Q,R is
(x - 1)(x -1) + (y - 2) (y + 2) + `lambda` (x - 1) = 0
`implies 1 - 4 - lambda = 0`
`implies lambda = - 3`
`:.` Required equation of circle is
`x^(2) + y^(2) - 5x = 0`
`:.` Centre `((5)/(2) , 0)` and radius `(5)/(2)`.


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