Exterior angleSum of the remote angles
Name: Date:
Find the angle marked x. Give each answer in degrees.
1 degrees
2 degrees
3 degrees
4 degrees
5 degrees
6 degrees
7 degrees
8 degrees
Exterior angle of a triangle worksheets
An exterior angle of a triangle equals the sum of the two remote interior angles — the two it does not touch. These free printable worksheets extend one side of each triangle, mark those two angles, and ask for the exterior angle x.
If they get stuck
Exterior angle of a triangle
The answer key prints on a separate page.
What's on this sheet
It is the companion fact to the angle sum, and it comes straight out of it: the exterior angle and its neighbor make a straight line (180°), the three interior angles also make 180°, so the exterior angle must equal the other two interior angles added together. Once a child sees that, the work is a single addition.
Why this sheet works
The mistake the fact is built to catch is reaching for the neighbor. The exterior angle skips the interior angle right beside it and adds the two far ones — so the sheet marks the two remote angles and leaves the adjacent one off the page, which is the picture the theorem describes.
How this one works
One question from a sheet like this one, worked a step at a time — with a sentence saying what just happened and why.
Exterior angle of a triangle, step by step