ACT Preparation / Unit 13 ACT 1205 short lesson, about 20 seconds
Corresponding and Same-Side Interior Angles
Captions available
The idea
With parallel lines and a transversal, corresponding angles, in matching positions at each crossing, are equal. Same-side interior angles add to 180°.
In practice
With a 65° angle at the upper crossing, its corresponding angle below is 65°, and its same-side interior partner is 115°.
Where people slip
Same-side interior angles are supplementary, not equal: the one pair that adds instead of matching.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
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