Find the coordinates of the circumcentre of the triangle whose vertices are (3, 0), (-1, -6) and (4,-1). Also, find its circumradius.
Coordinates of points on a circle are A (3, 0), B(-1, -6) and C(4,-1)
Let the coordinates of the centre of the circle be O(x, y)
Using distance formula =
Since the distance of the points A, B and C will be equal from the center, therefore
⇒ OA = OC
On squaring both sides, we get
=
⇒ x2 + 9 - 6x + y2 = x2 + 2x +1 + y2 + 36 + 12y
⇒ -8x - 12y = 28
⇒ 2x + 3y = -7------------- (1)
Similarly, OC = OB
On squaring both sides, we get
=
⇒ x2 + 16 - 8x + y2 + 1 + 2y = x2 + 1 +2x + y2 + 36 + 12y
⇒ -10x - 10y = 20
⇒ x + y = -2 ------------- (2)
Solving eqn (1) and (2), we get
x = 1; y = -3
Coordinates of circum center are (1, -3)
Circum radius of the circle = OA =
=
= units