Circumference and Area of Circles

Front

The distance from the center of the circle to any point on the circle is called the _____________.

Back

radius

Front

The distance across the circle from one side to the other, that passes through the center is called the ___________.

Back

diameter

Front

What is the formula for the circumference of a circle?

Back

C = 2πr or C = πd, where r is the radius and d is the diameter.

Front

What is the formula for the area of a circle?

Back

A = πr², where r is the radius.

Front

If the radius of a circle is 7 units, what is the area?

Back

A = π(7)² = 49π ≈ 153.94 units².

Front

If the diameter of a circle is 10 units, what is the radius?

Back

Radius = Diameter / 2 = 10 / 2 = 5 units.

Front

What is the circumference of a circle with a radius of 3 units?

Back

C = 2π(3) = 6π ≈ 18.84 units.

Front

If the area of a circle is 28.26 units², what is the radius?

Back

r = √(A/π) = √(28.26/π) ≈ 3 units.

Front

What is the diameter of a circle with a radius of 4 inches?

Back

Diameter = 2 × Radius = 2 × 4 = 8 inches.

Front

If a circle has a circumference of 31.4 units, what is the diameter?

Back

Diameter = Circumference / π = 31.4 / π ≈ 10 units.