Area and Circumference of Circles

Front

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

Back

A = π·r², where A is the area and r is the radius.

Front

What is the relationship between diameter and radius?

Back

The diameter is twice the radius. d = 2r.

Front

What is the circumference of a circle?

Back

The distance around the circle, calculated as C = π·d or C = 2π·r.

Front

If the radius of a circle is 5 cm, what is its area?

Back

A = π·(5)² = 25π ≈ 78.54 cm².

Front

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

Back

C = π·d = π·10 ≈ 31.42 inches.

Front

What is the radius of a circle with a diameter of 14 cm?

Back

Radius = Diameter / 2 = 14 cm / 2 = 7 cm.

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 convert diameter to radius?

Back

Divide the diameter by 2.

Front

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

Back

A = π·(3)² = 9π ≈ 28.27 m².

Front

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

Back

C = 2π·4 = 8π ≈ 25.13 inches.