Area and Circumference of Circles

Front

What is the formula for the circumference of a circle?

Back

C = 2πr, where C is the circumference and r is the radius.

Front

What is the formula for the area of a circle?

Back

A = πr², where A is the area and r is the radius.

Front

What is the radius of a circle?

Back

The measurement from the center of a circle to an edge of the circle.

Front

What is the diameter of a circle?

Back

The measurement from one edge of the circle to the opposite edge, passing through the center. It is twice the radius.

Front

If a circle has a radius of 6 inches, what is its circumference?

Back

12π or about 37.68 inches.

Front

If a circle has a radius of 12.5 mm, what is its circumference?

Back

78.5 mm.

Front

What does π (pi) represent in circle calculations?

Back

π is a constant approximately equal to 3.14, used in calculations involving circles.

Front

How do you find the area of a circle with a radius of 10 cm?

Back

A = π(10)² = 100π or about 314.16 cm².

Front

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

Back

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

Front

What is the circumference of a circle with a diameter of 20 cm?

Back

C = πD = 20π or about 62.83 cm.