Angles in parallel linesAlternate angles
Name: Date:
The two lines are parallel. Find x.
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Alternate angles worksheets
Alternate angles sit on opposite sides of the crossing line, between the two parallels, and they are equal. These free printable worksheets draw the figure, mark one, and ask for the other.
If they get stuck
Alternate angles
The answer key prints on a separate page.
What's on this sheet
The letter Z is the picture here, and the two angles are tucked into its corners. They are on opposite sides of the transversal and both inside the parallel pair, which is what "alternate" and "interior" mean before either word is used. Finding the Z is the whole method.
Why this sheet works
It is worth knowing that this rule is not separate from corresponding angles. An alternate pair is a corresponding pair with one of them swapped for the angle opposite it across the crossing, and those two are equal too. A child who sees the connection has two rules resting on one fact rather than two facts to keep apart.
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.
Alternate angles, step by step