JEE Main2016MathematicsCircleActual
A circle passes through - 2 , 4 and touches the y - axis at 0 , 2 . Which one of the following equations can represent a diameter of this circle ?
Options
- A2 x - 3 y + 10 = 0
- B3 x + 4 y - 3 = 0
- C4 x + 5 y - 6 = 0
- D5 x + 2 y + 4 = 0
Correct answer
A. 2 x - 3 y + 10 = 0
Step-by-step solution
As y - axis is tangent to the circle therefore the centre of the circle would be x , 2 and distance of centre from 0 , 2 and - 2 , 4 should be equal. ∴ h 2 + 0 2 = h + 2 2 + 2 2 ⇒ h 2 = h 2 + 4 h + 4 + 4 ⇒ h = - 2 Hence, centre is - 2 , 2 . ∴ 2 x - 3 y + 10 = 0 is the diameter, as centre lies on it.