Real World Area and Circumference Flashcard

Front

What is the formula for the circumference of a circle?

Back

Circumference = π × diameter (C = πd) or Circumference = 2 × π × radius (C = 2πr)

Front

What is the value of π (pi) commonly approximated as?

Back

π is commonly approximated as 3.14.

Front

If a circle has a diameter of 10 inches, what is its circumference?

Back

Circumference = π × diameter = 3.14 × 10 = 31.4 inches.

Front

What is the formula for the area of a circle?

Back

Area = π × radius² (A = πr²)

Front

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

Back

Area = π × radius² = 3.14 × 5² = 78.5 square meters.

Front

What is the relationship between diameter and radius?

Back

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

Front

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

Back

Diameter = Circumference / π.

Front

If the circumference of a circle is 31.4 cm, what is its diameter?

Back

Diameter = Circumference / π = 31.4 / 3.14 = 10 cm.

Front

What is the circumference of a circle with a radius of 7 feet?

Back

Circumference = 2 × π × radius = 2 × 3.14 × 7 = 43.96 feet.

Front

What is the area of a circle with a diameter of 8 inches?

Back

Radius = 4 inches; Area = π × radius² = 3.14 × 4² = 50.24 square inches.