Angle pairsEvery angle fact
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
Complementary and supplementary angles worksheets
Three years after naming angles, a child is asked to work one out from another. These free printable worksheets draw a pair of angles and mark one with x.
If they get stuck
Complementary and supplementary angles
The answer key prints on a separate page.
What's on this sheet
The arithmetic is deliberately trivial: one subtraction from 90 or from 180. The whole difficulty is knowing which fact applies to the picture in front of you, so the three relationships are drawn so they cannot be confused — a square corner mark for complementary, a ruled straight line for supplementary, and two full lines crossing for vertical.
Why this sheet works
Vertical angles are the ones that catch children out, because the answer is the number they were given rather than something taken away from it. They stay in the mix for exactly that reason: a page where every answer needs a subtraction teaches subtraction, not angle facts.
How this one works
Vertical angles
28°andx
opposite=equal
28°→28°
- Two straight lines crossing. This is the pair that is NOT a subtraction — nothing adds to 90 or 180 here, so reaching for either is the mistake.
- Angles opposite each other at a crossing are EQUAL. Each one is what is left when the same straight line is taken away from the same straight line, so they cannot differ.
- So x is 28° — the same as the one across from it, not 180 minus it.