Circles - Area and Circumference

Front

What is the formula for the area of a circle?

Back

Area = πr², where r is the radius.

Front

What is the formula for the circumference of a circle?

Back

Circumference = 2πr or Circumference = πd, where d is the diameter.

Front

What is a radius?

Back

A radius is a line segment from the center of the circle to any point on its circumference.

Front

What is a diameter?

Back

A diameter is a line segment that passes through the center of the circle and has its endpoints on the circumference.

Front

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

Back

Area = π(5)² = 25π ≈ 78.54 cm².

Front

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

Back

Radius = Diameter / 2 = 10 cm / 2 = 5 cm.

Front

What is the relationship between radius and diameter?

Back

The diameter is twice the length of the radius.

Front

What is the value of π (pi) approximately?

Back

π (pi) is approximately 3.14.

Front

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

Back

Circumference = 2πr.

Front

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

Back

Area = π(d/2)², where d is the diameter.