JEE Main 201511 AprilOnline
- Exam
- JEE Main
- Year
- 2015
- Date
- 11 April
- Mode
- Online
- Subject
- Mathematics
- Chapter
- Circle
JEE Main 2015 · 11 April · Online · Mathematics · Circle
If a circle passing through the point (- 1, 0) touches y -axis at...
If a circle passing through the point touches -axis at \left(0, 2\right)x$-intercept of the circle is
Options
- A
- B
- C
- D
Correct answer
D.
Step-by-step solution
Let be the centre of the circle
Equation of the circle is
Put \left(- 1,0\right){\left(- 1 - a\right)}^{2} + {\left(- 2\right)}^{2} = {a}^{2}1 + 2a + {a}^{2} + 4 = {a}^{2}2a = - 5a = - \dfrac{5}{2}{\left(x + \dfrac{5}{2}\right)}^{2} + {\left(y - 2\right)}^{2} = \dfrac{25}{4}= 2\sqrt{{g}^{2} - c}= 2\sqrt{\dfrac{25}{4} - 4}= 2\sqrt{\dfrac{9}{4}}= 3