Parts of a Circle ,Area and Circumference of a Circle

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

What is the diameter of a circle?

Back

The diameter is twice the length of the radius and is the distance across the circle through its center.

Front

What is the circumference of a circle?

Back

The circumference is the distance around the circle, calculated using the formula C = 2πr or C = πd.

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 the radius of a circle is 9, what is the area?

Back

A = π(9)² = 81π.

Front

If the diameter of a circle is 18, what is the radius?

Back

The radius is half of the diameter, so the radius is 9.

Front

What part of a circle is represented by a line from the center to the circumference?

Back

This line is called the radius.

Front

What part of a circle is represented by a line that passes through the center and touches both sides of the circle?

Back

This line is called the diameter.

Front

How do you calculate the circumference of a circle with a radius of 5?

Back

C = 2π(5) = 10π.

Front

What is the relationship between the diameter and the radius?

Back

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