Circumference and Area of Circles

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

What is the value of π (pi) approximately?

Back

π ≈ 3.14.

Front

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

Back

C = 2π(5) = 31.4 cm.

Front

If the diameter of a circle is 10 cm, what is its area?

Back

A = π(5)² = 78.5 cm².

Front

What is the relationship between radius and diameter?

Back

Diameter = 2 × Radius.

Front

If a circle has a radius of 7 cm, what is its area?

Back

A = π(7)² ≈ 153.94 cm².

Front

What is the circumference of a circle with a diameter of 12 cm?

Back

C = π(12) ≈ 37.68 cm.

Front

How do you convert diameter to radius?

Back

Radius = Diameter / 2.

Front

What is the area of a circle with a diameter of 16 cm?

Back

A = π(8)² ≈ 201.06 cm².