Circles

Front

What is a radius of a circle?

Back

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

Front

What is a diameter of a circle?

Back

The diameter is a straight line that passes through the center of the circle and touches two points on its boundary. It is twice the length of the radius.

Front

What is the circumference of a circle?

Back

The circumference is the distance around the circle, calculated as C = 2πr, where r is the radius.

Front

What is the area of a circle?

Back

The area is the amount of space inside the boundary of the circle, calculated as A = πr².

Front

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

Back

The radius is half of the diameter. r = d/2.

Front

What is the relationship between radius and diameter?

Back

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

Front

What is π (pi)?

Back

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

Front

If the radius of a circle is 5 ft, what is the area?

Back

A = π(5)² = 25π ≈ 78.54 square feet.

Front

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

Back

C = πd = π(10) ≈ 31.42 feet.

Front

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

Back

C = 2πr or C = πd.