9.3. Circles http://www.ck12.org
Solution:
The center of the circle is at (3, 1) and the radius of the circle isr=4. The equation is(x− 3 )^2 +(y− 1 )^2 =16.
Concept Problem Revisited
The reason why the graphing form of a circle looks like the Pythagorean Theorem is because eachxandycoordinate
along the outside of the circle forms a perfect right triangle with the radius as the hypotenuse.
Vocabulary
Theradiusof a circle is the distance from the center of the circle to the outside edge.
Thecenterof a circle is the point that defines the location of the circle.
Acircleis the collection of points that are equidistant from a given point.
Guided Practice
- Graph the following conic:(x+ 2 )^2 +(y− 1 )^2 = 1
- Translate the following conic from standard form to graphing form.
x^2 − 34 x+y^2 + 24 y+^7492 = 0 - Write the equation for the following circle.
Answers: