Geometry Activity: Equations of Circles
1. Draw a large triangle on a coordinate grid and record coordinates of the vertices.
2. Use a compass to construct 3 perpendicular bisectors of 3 sides of your triangle.
What do you notice?
3. Find the definition of a circumcenter in your textbook. What is it? Explain in your
own words. Label it on your graph and record its coordinates.
4. Use a compass to construct a circle circumscribed about your Triangle. How do
you do it? Explain.
5. What is the distance formula?
6. Find the distances from the circumcenter to each vertex of your triangle. What do
you notice?
7. What is the standard equation of a circle? How do you write it if you are given the
circle graph?
8. Write an equation of the circumscribed circle you’ve graphed.
9. Explain how to graph a circle if only its equation is given.