Glencoe Geometry Chapter 1 Vocabulary

Circumference Formula

C = 2πr

angle bisector

a line or line segment that cuts an angle into exactly two angles with equal measure

concave polygon

a polygon that has one or more sides that go into the interior of the polygon

acute angle

an angle measuring less than 90 degrees

perpendicular

at an angle of 90° to a given line, plane, or surface.

vertical angles

congruent two nonadjacent angles formed by two intersecting lines

supplementary angles

Two angles whose sum is 180 degrees

convex polygon

A convex polygon is defined as a polygon with all its interior angles less than 180°.

perimeter

The distance around the outside of a figure.

line segment

pg 13 a measurable portion of a line, with two endpoints

congruent

pg 15 having the same size and same shape

midpoint

pg 22 The point that divides a segment into two congruent segments

segment bisector

pg 25 a segment, ray, line, or plane that intersects a segment at its midpoint

exterior angle of a triangle

pg 31

obtuse angle

pg 32 An angle that measures more than 90 degrees but less than 180 degrees 180> m ∠ C >90

right angle

pg 32 an angle that measures 90 degrees

complementary angles

pg 42 two angles who's measures add up to 90 degrees are said to be ___________.

plane

pg 6 An endless flat surface

coplanar

pg 6 points or lines that are on the same plane are said to be ___________.

collinear

pg 6 points that lie on the same line are _______.

adjacent angles

two angles that share only a side