AP EAMCET201920 Apr 2019Morning ShiftMathematicsStraight LinesActual
Variable straight lines (y=m x+c ) make intercepts on the curve (y^2-4 a x=0 ) which subtend a right angle at the origin. Then the point of concurrence of these lines (y=m x+c ) is
Options
- A((4 a, 0) )
- B((2 a, 0) )
- C((-4 a, 0) )
- D((-2 a, 0) )
Correct answer
A. ((4 a, 0) )
Step-by-step solution
On homogenisation of the curve (y^2-4 a x=0 ) by line (y=m x+c ), we are getting combined equation of straight lines which subtend a right angle at the origin, so ( aligned y^2-4 a x ( y-m x c ) & =0 c+4 a m & =0 (i) aligned ) On putting the value of ' (c ) ' in the line, we get (y=m(x-4 a) ), represent family of line passes through ((4 a, 0) ). Hence, option (1) is correct.