ACT Preparation / Unit 13 ACT 1203 short lesson, about 20 seconds
Vertical Angles
Captions available
The idea
When two lines cross, the angles opposite each other are vertical angles, and vertical angles are equal. Neighboring angles are supplementary.
In practice
Lines crossing at a 70° angle make angles of 70°, 110°, 70° and 110°.
Where people slip
Vertical means opposite across the crossing point; it has nothing to do with up and down.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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