JEE MainMathematicsEllipse
Let the circle 2x^2 + 2y^2 - 15x - 10y = 0 intersect the x -axis and y -axis at the points P and Q , respectively, where neither P nor Q is the origin. If the line passing through P and Q is a tangent to the ellipse x^2 a^2 + y^2 9 = 1 (where a > 3 ), then the length of the latus rectum of this ellipse is
Options
- A3
- B24
- C6
- D9
Correct answer
A. 3
Step-by-step solution
To find the coordinates of P and Q , we determine the non-zero intercepts of the circle 2x^2 + 2y^2 - 15x - 10y = 0 on the coordinate axes. For the x -intercept, put y = 0 : 2x^2 - 15x = 0 x(2x - 15) = 0 . Since P is not the origin, x = 15 2 , so P ( 15 2 , 0 ) . For the y -intercept, put x = 0 : 2y^2 - 10y = 0 y(2y - 10) = 0 . Since Q is not the origin, y = 5 , so Q (0, 5) . The equation of the line passing through P and Q in intercept form is: x 15/2 + y 5 = 1 2x 15 + y 5 = 1 2x + 3y = 15 . Rewriting this in slop