Area and Circumference of Circles

Front

What is the formula for the circumference of a circle?

Back

C = πd or C = 2πr, where C is the circumference, d is the diameter, and r is the radius.

Front

How do you calculate the area of a circle?

Back

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

Front

What is the value of π (Pi) used in calculations?

Back

π is approximately 3.14 or can be used as the Pi button on a calculator.

Front

If the diameter of a circle is 14 cm, what is the radius?

Back

The radius is half of the diameter, so the radius is 7 cm.

Front

What is the circumference of a circle with a diameter of 19.1 ft using 3.14 for Pi?

Back

The circumference is 60.00 ft.

Front

What is the relationship between diameter and radius?

Back

The diameter is twice the length of the radius (d = 2r).

Front

What does the term 'radius' refer to in a circle?

Back

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

Front

What is the circumference of a circle with a radius of 5 cm?

Back

C = 2πr = 2 × 3.14 × 5 = 31.4 cm.

Front

How do you convert diameter to radius?

Back

To convert diameter to radius, divide the diameter by 2.

Front

What is the area of a circle with a radius of 10 cm?

Back

A = πr² = 3.14 × (10)² = 314 cm².