## How to Construct a Circle With a Compass – Video & Lesson Transcript

A compass is a metal instrument with two adjustable arms, one with a pointed metal tip and the other with a small mounted pencil, that can be used to draw circles or arcs. Some compasses have controls for locking the width of the arms and the height of the pencil tip.

### Constructing a Circle

Determine the radius – it may be a measurement or a distance between other points on the drawing. Tighten the grips on the pencil and compass point, as well as the hinge at the top.

### Example 1

To unlock this lesson, you must be a Study.com member. Use the distance on the drawing to set your compass width.

## How do you draw a circle with a ruler and a compass?

Step 1: Open the compass and use a ruler to measure the length of 5 units. Step 2: Mark a point O, which will serve as the circle’s center. Step 3: Place the pointer on this point, point O. Step 4: Turn the compass and drag the pencil around the center to complete the circle.

## How can I make a compass at home?

Let’s make a compass together.

- Fill the bowl halfway with water and float the u201ccompassu201d on the surface.
- Place the entire u201ccompassu201d on a flat surface and watch the needle try to align itself with the magnetic fields.

## How do we name a circle?

A circle is named after its center, so the circle to the right is called circle A because its center is at point A. Real-world examples of circles include a wheel, a dinner plate, and (the surface of) a coin. The diameter is the distance across a circle through the center.

## How do you draw a radius of 3 circles?

Step 1: Using a compass, draw a circle with a center of O and a radius of 3 cm.

- Step 2: Draw a secant through the center.
- Step 3: Place the compass on P and draw two arcs on opposite sides of OP.