Step 1: Identify the center of the circle from the graph

          NOTE: Locate the x- coordinate and y- coordinate of the center in the graph.

          EXAMPLE: from the graph x- coordinate = 0

                                                      y- coordinate = 0

                                    Center = (0, 0)

Step 2: Locate a point on the circumference of the circle.

Step 3: Calculate the given circle radius by the distance formula

NOTE: Radius = distance between center and point on the surface of the circle. So, use the Distance formula to find the equation of the circle.

d\ =\ \sqrt{\left(x_{2\ }-\ x_1\right)^2\ +\ \left(y_{2\ }\ -\ y_1\right)^2}\

EXAMPLE:Given points (2, 1)(10, 7)

r\ =\ \sqrt{\left(10\ -\ 2\right)^2\ +\ \left(7-1\right)^2}

r =\sqrt{64+36}

r= 64 + 36

r =\sqrt{100}

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Step 4: Substitute this values in the equation of a circle.

NOTE: Standard Form for the equation of the circle

Where center (h, k) and r- radius

EXAMPLE: (x-2)_{\ \ }^2+(y-1)^2=\ 100  

Step 5: Simplify the equation further