Unit 5 Equation of a Circle
How do you identify the DIAMETER given the EQUATION of a CIRCLE?
Find r by taking the square root of r². The diameter is 2r.
How do you identify a POINT on a CIRCLE given the CENTER and RADIUS?
First plug the center into h and k, and the radius for r into the equation of a circle on the formula sheet. Then plug the x and y from each point and see which one gives the correct r².
How do you plot a POINT on a CIRCLE given the CENTER and RADIUS?
On graph paper, plot the center. From the center count, either up, down, left or right the length of the radius. Then plot a point.
How do you find the EQUATION of a CIRCLE given the coordinates of the CENTER and a POINT on the circle?
The center is (h,k) in the equation. Just remember to change the signs. Substitute the point into x and y to find r².
How do you identify the CENTER given the EQUATION of a CIRCLE?
The center is (h,k). Don't forget to change the signs!
How do you identify the RADIUS given the EQUATION of a CIRCLE?
The radius is r. Take the square root of r².
How do you find the EQUATION of a CIRCLE given the coordinates of the endpoints of a DIAMETER?
Use midpoint formula to find center (h,k). Plug one of the points given into the equation for x and y into the calculator and that will give you r².
What formula is similar to the equation of a circle?
distance formula
The name of a circle is also called?
the center
How do you find the RADIUS of a circle given the CENTER and a POINT on the circle?
use the distance formula
