Angle
A point
Vertex
Line
An infinite set of points that extends forever in both directions infinitely
Line Segment
A section of a line connecting two endpoints with a specific length
Ray
Intersecting Lines
Adjacent Angles
Two angles that share a common side and vertex
Angle Bisector
A line or segment that divides an angle into 2 congruent angles
Perpendicular Lines
(always 2 steps in a proof)
Right Angle
Acute Angles
Angles less than 90 degrees
Obtuse Angles
Angles more than 90 degrees but less than 180 degrees
Straight Angle
An angle whose measure = 180 degrees
Complementary Angles
Angles that add up to = 90 degrees
Supplementary Angles
Angles that add up to = 180 degrees
Angles around a point
Add up to = 360 degrees
Linear Pair
2 Angles that form a line and add up to = 180 degrees
Vertical Angles
are congruent
Parallel Lines
Alternate Interior Angles
with 2 parallel lines cut by a transversal, alternate interior angles are congruent
Alternate Exterior Angles
with 2 parallel lines cut by a transversal, alternate exterior angles are congruent
Same Side Interior Angles
with 2 parallel lines cut by a transversal, same side interior angles are supplementary (add up to = 180 degrees)
Same Side Exterior Angles
with 2 parallel lines cut by a transversal, same side exterior angles are supplementary (add up to = 180 degrees)
Corresponding Angles
with 2 parallel lines cut by a transversal, corresponding angles are congruent
Lines are parallel when...
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