Circle Equations: Radius, Center & Write

Front

What is the standard equation of a circle?

Back

The standard equation of a circle with center (h, k) and radius r is (x - h)² + (y - k)² = r².

Front

What does the 'r' in the standard equation of a circle represent?

Back

r is the radius of the circle.

Front

How do you find the center of a circle from its equation?

Back

The center of a circle in the standard form (x - h)² + (y - k)² = r² is (h, k).

Front

What is the radius of a circle if its equation is (x - 2)² + (y + 3)² = 16?

Back

The radius is 4, since r² = 16.

Front

Write the equation of a circle with center (0, 0) and radius 5.

Back

The equation is x² + y² = 25.

Front

What is the radius of a circle given the equation (x + 1)² + (y - 2)² = 9?

Back

The radius is 3, since r² = 9.

Front

If the center of a circle is at (3, -4) and the radius is 2, what is the equation of the circle?

Back

The equation is (x - 3)² + (y + 4)² = 4.

Front

What does the term 'h' represent in the standard equation of a circle?

Back

h represents the x-coordinate of the center of the circle.

Front

What does the term 'k' represent in the standard equation of a circle?

Back

k represents the y-coordinate of the center of the circle.

Front

How do you determine the radius from the equation of a circle?

Back

The radius is the square root of the constant on the right side of the equation in standard form.