Calculating the length of a line segment

I can calculate the length of a line segment on a coordinate grid in all four quadrants or using the coordinate pairs.

Download all resources

Share activities with pupils

New

Year 10

Foundation

Calculating the length of a line segment

I can calculate the length of a line segment on a coordinate grid in all four quadrants or using the coordinate pairs.

Download all resources

Share activities with pupils

These resources will be removed by end of Summer Term 2025.

Switch to our new teaching resources now - designed by teachers and leading subject experts, and tested in classrooms.

View new resources

Slide deck

Download slide deck

Skip slide deck

Lesson details

Key learning points

Any line segment can be turned into a right-angled triangle by adding two lines which meet at 90°
Calculating the horizontal distance gives the length of one side
Calculating the vertical distance gives the length of the other side
These two shorter sides lengths can be used to calculate the length of the line segment
This can be done using Pythagoras' theorem

Keywords

Hypotenuse - The hypotenuse is the side of a right-angled triangle which is opposite the right angle.
Pythagoras' theorem - Pythagoras’ theorem states that the sum of the squares of the two shorter sides of a right-angled triangle is equal to the square of the hypotenuse.

Common misconception

Pupils may think that direction matters when determining the distance between two points.

Direction matters when dealing with displacement, not distance.

Consider using a map and asking pupils to find the shortest (straight-line) distance between two points on the map. You could use a map of your local area. Are the distances the same as what the pupils expected? Is anywhere 'closer' than pupils thought it should be?