Standard Form of a Circle and Center

Identify the center of the circle in general form.

• A

• B

• C

• D

Select the matching graph.

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Write the standard equation of the circle with the given center and radius; center (0, 0) and radius of 3.

• x² + y² = 4

• x² + y² = 81

• x² + y² = 9

• x² + y² = 3

A circle has the equation x² + y² - 12x + 8y + 3 = 0. Write the equation in standard form.

• (x - 6)² + (y + 4)² = 49

• (x + 4)² + (y - 6)² = 49

• (x - 6)² + (y + 4)² = 55

• x² + y² = 55

Change the following equation to standard form

• (x + 2)² + (y - 6)² = 48

• (x - 2)² + (y + 6)² = 48

• (x - 6)² + (y - 2)² = 48

• (x + 2)² + (y - 6)² = 48

What is the center for the circle with this equation x² + y² + 4x + 6y - 36 = 0?

• (-2, 5)

• (2, 7)

• (-2, -7)

• (-2, -3)

Determine the equation of the circle in standard form:

x² + y² + 4x + 6y - 36 = 0

• (x + 2)² + (y + 3)² = 49

• (x + 2)² + (y + 3)² = 13

• (x - 2)² + (y - 3)² = 49

• (x - 2)² + (y - 3)² = 13

A circle has the equation x² + y² + 10x - 4y + 20 = 0. Write it in standard form.

• (x - 5)² + (y + 2)² = 9

• (x + 5)² + (y - 2)² = 3

• (x + 5)² + (y - 2)² = 9

• (x - 5)² + (y + 2)² = 3

A circle has the equation x² + y² - 8x + 6y - 11 = 0. Write it in standard form.

• (x - 4)² + (y + 3)² = 36

• (x - 4)² + (y + 3)² = 6

• (x + 4)² + (y - 3)² = 36

• (x + 4)² + (y - 3)² = 6

Find the center and radius of the circle: x² + y² + 14x - 2y = -1.

• center = (-7, 2) radius = 3

• center = (-7, 1) radius = 7

• center = (-4, 1) radius = 7

• center = (-4, 2) radius = 3