Angle Relationships

Adjacent angles are two angles that share a common vertex and a common side, but do not overlap.

Complementary angles are two angles whose measures add up to 90 degrees.

Supplementary angles are two angles whose measures add up to 180 degrees.

Vertical angles are the angles opposite each other when two lines intersect. They are always equal.

Alternate interior angles are pairs of angles that are on opposite sides of a transversal and inside the two lines.

Corresponding angles are pairs of angles that are in the same position on two parallel lines in relation to a transversal.

Alternate exterior angles are pairs of angles that are on opposite sides of a transversal and outside the two lines.

Look for two angles that add up to 90 degrees, often indicated by a right angle symbol.

Look for two angles that add up to 180 degrees, often forming a straight line.

Vertical angles are always equal in measure.