Finding the Standard Equation of a Circle

x^2 + y^2 = 2r

(x - h)^2 + (y - k)^2 = r^2

x^2 + y^2 = r^2

(x + h)^2 + (y + k)^2 = r

(2, -2)

(4, -1)

(1, -4)

(-1, 4)

Radius and diameter

X and Y coordinates of the center

Diameter and circumference

X and Y intercepts

Using the midpoint formula

By doubling the distance from the center to a point

By squaring the center's coordinates

Through the distance formula between two points

Midpoint formula

Slope formula

Distance formula

Perimeter formula

9

36

3√5

45

6.71

9

3√5

√45

-x + 1

x + 1

x - 1

-x - 1

9

45

6.71

3

To simplify the equation

For easier graphing on the coordinate plane

To calculate the area of the circle

To determine the circumference