High School Math : Finding the Center and Radius

Study concepts, example questions & explanations for High School Math

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Example Questions

Example Question #2 : Quadratic Functions

Find the center and radius of the circle defined by the equation:

Possible Answers:

Correct answer:

Explanation:

The equation of a circle is:  where  is the radius and  is the center. 

In this problem, the equation is already in the format required to determine center and radius. To find the -coordinate of the center, we must find the value of  that makes  equal to 0, which is 3. We do the same to find the y-coordinate of the center and find that . To find the radius we take the square root of the constant on the right side of the equation which is 6.

Example Question #3 : Quadratic Functions

Find the center and radius of the circle defined by the equation:

Possible Answers:

Correct answer:

Explanation:

The equation of a circle is:  where  is the radius and  is the center. 

In this problem, the equation is already in the format required to determine center and radius. To find the -coordinate of the center, we must find the value of  that makes  equal to , which is . We do the same to find the y-coordinate of the center and find that . To find the radius we take the square root of the constant on the right side of the equation which is 10.

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