Circumference and Pi STAAR Review

Front

What is the formula to calculate the circumference of a circle?

Back

The circumference (C) of a circle can be calculated using the formula: C = 2πr, where r is the radius.

Front

What is the value of pi (π)?

Back

Pi (π) is approximately 3.14 and represents the ratio of the circumference of a circle to its diameter.

Front

If a circle has a radius of 10 inches, what is the circumference?

Back

Using the formula C = 2πr, the circumference is C = 2π(10) = 20π inches, approximately 62.83 inches.

Front

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

Back

The circumference of a circle is equal to π times the diameter (C = πd).

Front

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

Back

To find the radius (r) from the circumference (C), use the formula: r = C/(2π).

Front

What is the circumference of a circle with a radius of 4.5 cm?

Back

Using the formula C = 2πr, the circumference is C = 2π(4.5) = 9π cm, approximately 28.26 cm.

Front

What is the circumference of a circle with a radius of 3 cm?

Back

Using the formula C = 2πr, the circumference is C = 2π(3) = 6π cm, approximately 18.84 cm.

Front

If a circular tablecloth has a radius of 2.5 feet, what is the circumference?

Back

Using the formula C = 2πr, the circumference is C = 2π(2.5) = 5π ft, approximately 15.7 ft.

Front

What does it mean when we say pi is an irrational number?

Back

An irrational number cannot be expressed as a simple fraction; its decimal representation goes on forever without repeating.

Front

What is the diameter of a circle if the radius is 5 cm?

Back

The diameter (d) is twice the radius, so d = 2r = 2(5) = 10 cm.