Practice Flashcard - Circles

Front

What is the circumference of a circle?

Back

The circumference of a circle is the distance around it, calculated using the formula: C = πd or C = 2πr, where d is the diameter and r is the radius.

Front

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

Back

The diameter of a circle is twice the length of the radius. Formula: d = 2r.

Front

True or False: The circumference of a circle is greater than its diameter.

Back

True.

Front

How do you calculate the area of a circle?

Back

The area of a circle is calculated using the formula: A = πr², where r is the radius.

Front

If a circle has a diameter of 20 inches, what is its radius?

Back

The radius is 10 inches, since r = d/2.

Front

What is the value of π (pi) approximately?

Back

π is approximately 3.14.

Front

True or False: The radius of a circle is twice its diameter.

Back

False.

Front

What is the formula to find the diameter of a circle if you know the radius?

Back

The formula is d = 2r.

Front

If a bicycle wheel has a diameter of 18 inches, how far does it travel in one rotation?

Back

The distance traveled in one rotation is equal to the circumference, which is C = πd = 3.14 * 18 = 56.52 inches.

Front

If a circle has a radius of 5 inches, what is its area?

Back

The area is A = πr² = 3.14 * (5)² = 78.5 square inches.