Circles

Front

What is the standard equation of a circle with center (h, k) and radius r?

Back

(x - h)² + (y - k)² = r²

Front

What is the radius of a circle?

Back

The radius is the distance from the center of the circle to any point on its circumference.

Front

What is the diameter of a circle?

Back

The diameter is twice the length of the radius and is the longest distance across the circle.

Front

How do you find the circumference of a circle?

Back

Circumference = 2πr, where r is the radius.

Front

How do you find the area of a circle?

Back

Area = πr², where r is the radius.

Front

What is the relationship between the radius and diameter?

Back

The diameter is equal to twice the radius (d = 2r).

Front

If a circle has a radius of 5, what is its area?

Back

Area = π(5)² = 25π.

Front

If a circle has a circumference of 31.4, what is its radius?

Back

Radius = Circumference / (2π) = 31.4 / (2π) ≈ 5.

Front

What is the measure of a central angle in a circle?

Back

A central angle is an angle whose vertex is at the center of the circle and whose sides intersect the circle.

Front

What is an inscribed angle in a circle?

Back

An inscribed angle is formed by two chords in a circle which have a common endpoint.