JEE Main2015MathematicsParabolaActual
If the tangent to the conic, y - 6 = x 2 at ( 2 , 10 ) touches the circle, x 2 + y 2 + 8 x - 2 y = k (for some fixed k ) at a point α , β ; then ( α , β ) is
Options
- A- 7 17 , 6 17
- B- 8 17 , 2 17
- C- 6 17 , 10 17
- D- 4 17 , 1 17
Correct answer
B. - 8 17 , 2 17
Step-by-step solution
The equation of tangent ( T = 0 ) would be 1 2   y + 10 -   6 = 2 x 4 x - y + 2 = 0 The center of the circle is ( - 4 , 1 ) and the point of contact would be the foot of perpendicular from ( - 4 , 1 ) on 4 x - y + 2 = 0 α + 4 4 = β - 1 - 1 =   - - 16 - 1 + 2 4 2 + 1 2 α + 4 4 = 15 17 and β - 1 - 1 = 15 17 α =   - 8 17 , β =   - 15 17 + 1 = 2 17 Hence option - 8 17 ,   2 17 is correct.