Circles

Question 1

A circle is

Answer 1

a round two-dimensional shape.

It is NOT a polygon.

Question 2

The dot in the middle of a circle is called the

Answer 2

center

Question 3

The line segment from the center of the circle to the circle is called the

Answer 3

radius.

The radius is half of the diameter.

Question 4

Any line segment that connects two points on the circle and goes through the center of the circle is called the

Answer 4

diameter

The diameter is twice the length of the radius.

Question 5

A line segment that connects two points on the circle is called a

Answer 5

chord

The diameter is a special example of a chord.

Question 6

Half of a circle is called a

Answer 6

Semicircle

Question 7

The distance around a circle is called its

Answer 7

circumference.

You can also think of it as the perimeter of a circle.

Question 8

Area Formula for Circles

Answer 8

A = pi * r squared

A = pi * r^2

A = pi * radius * radius

Question 9

Circumference Formula

Answer 9

C = 2 * pi * radius

or

C = pi * diameter