Circles for 7th grade

Front

What is the formula for the circumference of a circle?

Back

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

Front

What is the area of a circle?

Back

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

Front

What is the diameter of a circle?

Back

The diameter is the distance across the circle through the center, equal to twice the radius.

Front

What is the radius of a circle?

Back

The radius is the distance from the center of the circle to any point on its circumference.

Front

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

Back

A = π(7)² ≈ 153.9 cm².

Front

If the diameter of a circle is 10 m, what is the circumference?

Back

C = πd = π(10) ≈ 31.4 m.

Front

What is π (pi)?

Back

π is a mathematical constant approximately equal to 3.14, representing the ratio of the circumference of a circle to its diameter.

Front

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

Back

d = 2r, where d is diameter and r is radius.

Front

What is the relationship between radius and diameter?

Back

The diameter is twice the length of the radius.

Front

What is the approximate area of a pizza with a diameter of 14 inches?

Back

A = π(7)² ≈ 154 square inches.