Radius, Diameter, and Circumference

Front

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

Back

Circumference = 2 × π × radius or Circumference = π × diameter.

Front

What is the relationship between the radius and diameter of a circle?

Back

The diameter is twice the radius (Diameter = 2 × Radius).

Front

If the radius of a circle is 3 feet, what is the circumference?

Back

Circumference = 2 × π × 3 ≈ 18.85 feet.

Front

What is the definition of diameter?

Back

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

Front

How do you find the radius if you know the circumference?

Back

Radius = Circumference / (2 × π).

Front

What is the approximate value of π (pi)?

Back

π (pi) is approximately 3.14.

Front

If a circular garden has a circumference of 31.4 feet, what is its radius?

Back

Radius = Circumference / (2 × π) = 31.4 / (2 × 3.14) ≈ 5 feet.

Front

What is the circumference of a circle with a diameter of 10 inches?

Back

Circumference = π × diameter = π × 10 ≈ 31.4 inches.

Front

What is the area of a circle with a radius of 4 feet?

Back

Area = π × radius² = π × 4² ≈ 50.27 square feet.

Front

What is the formula for the area of a circle?

Back

Area = π × radius².