How to bisect lines and angles

Part ofShape, space and measures

To play this video you need to enable JavaScript in your browser.

This video can not be played

A one-minute guide on how to bisect lines and angles.

How to bisect a line

Skip image gallery

Image caption,
WHAT YOU NEED: a ruler, a compass and a pencil.
Image caption,
STEP 1: Draw a straight line with a ruler.
Image caption,
STEP 2: Put the pin of a compass at the end of the line you want to bisect. Set the compass to more than half the length of the line, and draw an arc crossing the line.
Image caption,
STEP 3: Keep the width of the compass the same, and from the opposite end of the line draw another arc.
Image caption,
STEP 4: Mark the two points where the curved arcs cross each other. Then use a ruler to draw a line joining the points.
Image caption,
The line cuts the original line exactly in half, and is perpendicular to it. You have bisected a line!

How to bisect an angle

Skip image gallery

Image caption,
WHAT YOU NEED: a ruler, a compass, and a pencil.
Image caption,
STEP 1: Using a ruler draw two straight lines to make an angle.
Image caption,
STEP 2: Put the pin of the compass at the point of the angle. Set the other end of the compass to a point most of the way up one of the lines and draw an arc across each line. Mark the points where the arc crosses each line.
Image caption,
STEP 3: Place the pin of the compass on one of the marks that you've made. Draw an arc across the open end of the angle...
Image caption,
...and making sure to keep the compass the same width, place the pin on the second mark to draw another arc that crosses the first. Mark the point where the arcs cross.
Image caption,
STEP 4: Using a ruler, draw a line from the point of the angle to the mark where the two arcs cross.
Image caption,
This line splits the angle exactly in half. You have bisected an angle!

To play this video you need to enable JavaScript in your browser.

This video can not be played

Where next?

Want to dive deeper? Explore more with Bitesize.

Shape, space and measures

More on Shape, space and measures

Find out more by working through a topic

Points of the compass
count
40 of 50
Triangles and quadrilaterals
count
41 of 50
Polygons
count
42 of 50
WATCH: How to draw a regular hexagon, square and triangle
count
43 of 50