# What is the general equation of a circle which passes through #A#(1,1), #B#(2,-1),and #C#(2,3)?

##### 1 Answer

#### Explanation:

First plot the points out.

Let

An important concept is that a triangle formed by joining the two ends of a diameter and any other point on the circumference will always be a right angle triangle.

We want to find a diameter on our circle. Therefore we want to construct a right angle triangle with all 3 points on the circumference of the circle.

To do so, we observe that there must be a point,

Try to understand why point

Now we know that

The radius is

The equation of the circle is: