Find the equation of the circle which passes through (3, - 2), (- 2, 0) and has its centre on the line 2x – y = 3.
Given that we need to find the equation of the circle which passes through (3, - 2), (- 2,0) and has its centre on the line 2x - y = 3. ..... (1)
We know that the standard form of the equation of the circle is given by:
⇒ x2 + y2 + 2ax + 2by + c = 0 .....(2)
Substituting centre (- a, - b) in (1) we get,
⇒ 2(- a) - (- b) = 3
⇒ - 2a + b = 3
⇒ 2a - b + 3 = 0 ......(3)
Substituting (3, - 2) in (2), we get
⇒ 32 + (- 2)2 + 2a(3) + 2b(- 2) + c = 0
⇒ 9 + 4 + 6a - 4b + c = 0
⇒ 6a - 4b + c + 13 = 0 ..... (4)
Substituting (- 2,0) in (2), we get
⇒ (- 2)2 + 02 + 2a(- 2) + 2b(0) + c = 0
⇒ 4 + 0 - 4a + c = 0
⇒ 4a - c - 4 = 0 ..... (5)
Solving (3), (4) and (5) we get,
⇒
Substituting these values in (2), we get
⇒
⇒ x2 + y2 + 3x + 12y + 2 = 0
∴ The equation of the circle is x2 + y2 + 3x + 12y + 2 = 0.