
Angles in the same plane that have a common vertex and a common side, but no common interior points.
Adjacent Angles:

Angles formed when a third line (a transversal) crosses two other lines. These angles are on opposite sides of the transversal and are outside the other two lines. When the two other lines are parallel, the __________ ___________ ___________ are equal.
Alternate Exterior Angles:

Pairs of angles formed when a third line (a transversal) crosses two other lines. These angles are on opposite sides of the transversal and are in between the other two lines. When the two other lines are parallel, the __________ ____________ __________ are equal.
Alternate Interior Angles:

Two angles whose sum is 90 degrees.
Complementary Angles:

Having the same size, shape and measure. Two figures are ____________ if all of their corresponding measures are equal.
Congruent:

Angles that have the same relative positions in geometric figures.
Corresponding Angles:

The property of a polygon whose angles are all congruent.
Equiangular:

The property of a polygon whose sides are all congruent.
Equilateral:

Two lines in a plane that cross each other. Unless two lines are coincidental, parallel, or skew, they will intersect at one point.
Intersecting Lines:

Adjacent, supplementary angles. Excluding their common side, a linear pair forms a straight line.
Linear Pair:

Two lines are parallel if they lie in the same plane and they do not intersect.
Parallel Lines:

Two lines are ____________ if they intersect at a right angle.
Perpendicular Lines:

A polygon that is both equilateral and equiangular.
Regular Polygon:

Two lines that do not lie in the same plane (therefore, they cannot be parallel or intersect).
Skew Lines:

Two angles whose sum is 180 degrees.
Supplementary Angles:

A line that crosses two or more lines.
Transversal:

Two nonadjacent angles formed by intersecting lines or segments. Also called opposite angles.
Vertical Angles:

