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.
Kid stuck on one? You don’t just get the sheet.
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 neighbour 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 neighbour. 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 this sheet, worked through a step at a time.
The exterior angle
x=60°+65°
60°+65°=125°
x=125°
- An exterior angle of a triangle equals the sum of the two remote interior angles — the two it does not sit against. Here those are 60° and 65°.
- Add them: 60 + 65 = 125.
- So x = 125°.