Conic Sections: Circles

think icon Think & Click: Equations of Circles

Now, you try. Complete the Think & Click activity by looking at each problem below, thinking about it, and then clicking on the question to reveal the solution.

What is the equation of the circle centered at the point (3, 4) with radius 3?
 
x minus 3 quantity squared plus y minus 4 quantity squared equals 9
 

What is the equation of the circle graphed here:

circle through the points (0, negative 1), (negative 2, 1), (negative 4, negative 1) and (negative 2, negative 3)
 

Center: (-2, -1)
Radius: 2
x plus 2 quantity squared plus y plus 1 quantity squared equals 4