Geometry Chapter 1 Vocabulary

The three undefined terms in geometry are...

A pair of angles whose measures have a sum of 180 degrees

• vertical angles

• supplementary angles

• obtuse angles

• complementary angles

A rule that is accepted without proof

• angle

• theorem

• postulate

• midpoint

An angle whose measure is 90 degrees

• straight angle

• complementary angle

• acute angle

• right angle

A ray that divides an angle into two adjacent angles that are congruent

• opposite rays

• sides

• angle bisector

• acute angle

Points that lie on the same plane

• midpoint

• coplanar

• ordered pairs

• collinear

An angle that has a measure greater than 90 degrees but less than 180 degrees

• vertical angle

• obtuse angle

• linear pair of angles

• straight angle

Two angles that have the same measure

• congruent angles

• acute angles

• linear pairs

• adjacent angles

A pair of angles whose measures have a sum of 90 degrees

• vertical angles

• supplementary angles

• straight angles

• complementary angles

An angle that has a measure greater than 0 but less than 90

• adjacent angles

• acute angle

• obtuse angle

• straight angle