An html 5 applet generates the graph of a circle. The equations of the circle is of the form:
where (h , k) is the center of the circle and r its radius.
As an exercise, you need to find an equation to the circle generated. And you can check your answer.
Interactive Tutorial1 - click on the button "New Circle" to generate a new circle whose center is also plotted.
2 - From the graph, determine h and k which are the x and y coordinates of the center of the circle respectively. Then find a point on the graph of the circle and use it to find the radius r. Then write the equation as follows:
More References and linkstutorial on circles
Match Equations of Circles to Graphs. Excellent interactive activity where equations of circles are matched to graphs.
Three Points Circle Calculator.