Question

Write the equations of the circle in general form.

1. Points on circle (0,0), (0,8), (6,0)
2. Points on circle (1, -1), (2, -2), (0,-2).


I don't know how to solve this given the fact that I don't know what the center or the radius of the circle is.

Answer 1

points with the same x or y coordinate represent vertical or horizontal chords of the circle
the perpendicular bisectors of the chords are diameters, and they give one of the coordinates of the center
you can use the distance formula to find the other coordinate of the center

1. the center of the circle is (x,4)

2. the center of the circle is (1,y)