front 1 Angle | back 1 ![]() |
front 2 A point | back 2 ![]() |
front 3 Vertex | back 3 ![]() |
front 4 Line | back 4 ![]() An infinite set of points that extends forever in both directions infinitely |
front 5 Line Segment | back 5 ![]() A section of a line connecting two endpoints with a specific length |
front 6 Ray | back 6 ![]() |
front 7 Intersecting Lines | back 7 ![]() |
front 8 Adjacent Angles | back 8 ![]() Two angles that share a common side and vertex |
front 9 Angle Bisector | back 9 ![]() A line or segment that divides an angle into 2 congruent angles |
front 10 Perpendicular Lines | back 10 ![]() (always 2 steps in a proof) |
front 11 Right Angle | back 11 ![]() |
front 12 Acute Angles | back 12 ![]() Angles less than 90 degrees |
front 13 Obtuse Angles | back 13 ![]() Angles more than 90 degrees but less than 180 degrees |
front 14 Straight Angle | back 14 ![]() An angle whose measure = 180 degrees |
front 15 Complementary Angles | back 15 ![]() Angles that add up to = 90 degrees |
front 16 Supplementary Angles | back 16 ![]() Angles that add up to = 180 degrees |
front 17 Angles around a point | back 17 ![]() Add up to = 360 degrees |
front 18 Linear Pair | back 18 ![]() 2 Angles that form a line and add up to = 180 degrees |
front 19 Vertical Angles | back 19 ![]() are congruent |
front 20 Parallel Lines | back 20 ![]() |
front 21 Alternate Interior Angles | back 21 ![]() with 2 parallel lines cut by a transversal, alternate interior angles are congruent |
front 22 Alternate Exterior Angles | back 22 ![]() with 2 parallel lines cut by a transversal, alternate exterior angles are congruent |
front 23 Same Side Interior Angles | back 23 ![]() with 2 parallel lines cut by a transversal, same side interior angles are supplementary (add up to = 180 degrees) |
front 24 Same Side Exterior Angles | back 24 ![]() with 2 parallel lines cut by a transversal, same side exterior angles are supplementary (add up to = 180 degrees) |
front 25 Corresponding Angles | back 25 ![]() with 2 parallel lines cut by a transversal, corresponding angles are congruent |
front 26 Lines are parallel when... | back 26 alternate interior angles are congruent OR alternate exterior angles are congruent OR corresponding angles are congruent OR same side interior angles are supplementary OR same side exterior angles are supplementary |