Circles

Front

What is the formula for finding the area of a circle?

Back

A = π·r²

Front

What is the formula for finding the circumference of a circle?

Back

C = 2·π·r or C = π·d

Front

What is the diameter of a circle?

Back

The diameter is the distance across the circle through its center, equal to twice the radius.

Front

If the radius of a circle is 6 cm, what is the diameter?

Back

The diameter is 12 cm.

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

How do you calculate the circumference of a circle with a diameter of 6 meters?

Back

C = π·d = π·6 ≈ 18.84 m.

Front

What is the relationship between diameter and radius?

Back

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

Front

What is the area of a circle with a radius of 3 cm?

Back

A = π·r² = π·(3)² = 28.27 cm² (approximately).

Front

What is a chord in a circle?

Back

A chord is a line segment with both endpoints on the circle.

Front

What is a tangent to a circle?

Back

A tangent is a line that touches the circle at exactly one point.