Circles - Review After Flashcard Unit 3 IM

Front

What is the formula for the circumference of a circle?

Back

C = 2πr, where C is the circumference and r is the radius.

Front

What is the formula for the area of a circle?

Back

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

Front

If a circle has a radius of 7 inches, what is its circumference?

Back

C = 2π(7) = 14π inches.

Front

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

Back

A = π(5)² = 25π square inches.

Front

What is the relationship between diameter and radius?

Back

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

Front

If the circumference of a circle is 31.4 inches, what is the radius?

Back

r = C / (2π) = 31.4 / (2π) = 5 inches.

Front

What is the value of π (pi) approximately?

Back

π is approximately 3.14.

Front

If the area of a circle is 50π square inches, what is the radius?

Back

r = √(A/π) = √(50) = approximately 7.07 inches.

Front

What is the formula to find the radius if the circumference is known?

Back

r = C / (2π).

Front

What is the perimeter of a circle commonly referred to as?

Back

The perimeter of a circle is commonly referred to as the circumference.