Geometry Angle relationships Vocabulary

right angle

90 degrees

perpendicular lines

Lines that intersect to form right angles

Adjacent angles

angles that are next to eachother

Sum of all angles in a polygon

The number of sides minus 2 times 180 S=(n-2)180

transversal cuts parallel

a line that intersects two or more lines, 8 angles formed

alternate exterior angles

angles that are on opposite (alternate) sides of the transversal and are on the OUTSIDE (or exterior) of the parallel lines. They are EQUAL

alternate interior angles

angles that are on opposite (or alternate) sides of the transversal and are on the INSIDE (or interior) of the parallel lines. They are EQUAL

corresponding angles

angles that share the same position on 2 parallel lines that are cut by the same transversal

congruent angles in a transversal

angles with the same measure

obtuse angle

greater than 90 degrees

acute angle

less than 90 degrees

parallel line

lines in the same plane that never intersect

Vertical angles

opposite angles that have the same measure, the share a vertex

Angles in a triangle

the sum is 180 degrees a+b+c=180

Exterior angle measure of a triangle

the sum of the measures of the 2 non-adjacent interior angles

Supplementary angles

two angles with the sum of 180 degrees, make a linear pair (next to each other)

Complimentary angles

two angles with the sum of 90 degrees

Prove Congruency

1) Vertical Angles 2) Corresponding Angles 3) Alternate Interior Angles 4) Alternate Exterior Angles

Tools to help find angle measures

Supplementary angles ( angles on a straight line adding up to 180)

vertex

The common endpoint of an angle