JEE Main202331 Jan 2023Morning ShiftMathematicsCircleActual
Let a circle C 1 be obtained on rolling the circle x 2 + y 2 - 4 x - 6 y + 11 = 0 upwards 4 units on the tangent T to it at the point 3 , 2 . Let C 2 be the image of C 1 in T . Let A and B be the centers of circles C 1 and C 2 respectively, and M and N be respectively the feet of perpendiculars drawn from A and B on the x -axis. Then the area of the trapezium AMNB is:
Options
- A2 2 + 2
- B4 1 + 2
- C3 + 2 2
- D2 1 + 2
Correct answer
B. 4 1 + 2
Step-by-step solution
We have, x 2 + y 2 - 4 x - 6 y + 11 = 0 ⇒ x - 2 2 + y - 3 2 = 2 Centre ≡ 2 , 3 Radius r = 2 units Equation of tangent at 3 , 2 is 3 x + 2 y - 2 x + 3 - 3 y + 2 + 11 = 0 ⇒ x = y = 1       . . . 1 On rolling the given circle upward 4 units on the tangent 1 , centre of the circle also moving 4 unit upward, so Centre of C 1 is = 2 + 2 2 , 3 + 2 2 A 2 + 2 2 , 3 + 2 2 Centre of C 2 is B 4 + 2 2 , 1 + 2 2 So, M 2 + 2 2 , 0 and N 4 + 2 2 , 0 . ∴ area of trapezium = 1 2 A M + B N ×