Most Important Selected Qs for JEE AdvancedMathematicsEllipse
A straight line through a point P( , 2),( 0) meets the ellipse x^2 9 + y^2 4 =1 at A and D & meets axes at B and C such that PA, PB, PC and PD are in GP, then ' ' can lie in interval
Options
- A[7, )
- B(-12,-8)
- C(-5,0)
- D(10, )
Correct answer
D. (10, )
Step-by-step solution
Any point on the line through P( , 2) is ( +r , 2+r ) and meets the ellipse x^2 9 + y^2 4 =1 at A and D ( +r )^2 9 + (2+r )^2 4 =1 (4 ^2 +9 ^2 ) r^2+4(2 +9 ) r+4 ^2=0 P A P D= 4 ^2 4 ^2 +9 ^2 Again solving with x y=0 PB PC = 2 4 ^2 4 ^2 +9 ^2 = 2 aligned & 2 2 +5 2 =13 & -1 13 4 ^2+25 1 | | 6 aligned