Circles

Circles

Draw a circle

To make a circle: Draw a curve that is "radius" away from a central point.

And so: All points are the same distance from the center.

You can draw it yourself: Put a pin in a board, put a loop of string around it, and insert a pencil into the loop. Keep the string stretched and draw the circle!

Different Parts of a Circle

Describe different parts of a circle.

The radius of the circle

The radius of the circle is a straight line drawn from the center to the boundary line or the circumference. The plural of the word radius is radii.

The diameter

The diameter is the line crossing the circle and passing through the center. It is twice the length of the radius.

The circumference of a circle

The circumference of a circle is the boundary line or the perimeter of the circle.

An arc

An arc is a part of the circumference between two points or a continuous piece of a circle. The shorter arc between two points is called the minor arc. The longer arc between two points is called the major arc.

The chord

The chord is a straight line joining two points on the circumference points of a circle. The diameter is a special kind of the chord passing through the center.

A semi-circle

A semi-circle is an arc which is half of the circumference.

A tangent

A tangent is a straight line which touches the circle. It does not cut the circumference. The point at which it touches is called the point of contact.