vocabulary and angles

undefined terms

point, line, plane

Collinear

points that reside on the same line

Colpanar

points that reside on the same plane

line segment

a portion of a line with two endpoints

ray

A portion of a line, with one endpoint, that continues without end in one direction

equal

having the same number value

congruent

Having the same size and shape

bisect

a segment cut in two equal parts

Midpoint

The point that bisects a line segment

angle

two rays that intersect at their endpoints

right angle

an angle that measures 90 degrees

acute angle

an angle that measures less than 90 degrees and greater than 0

obtuse angle

An angle that measures more than 90 degrees but less than 180 degrees

protractor

A tool used to measure angles

postulate

a statement that is accepted as true without proof

angle bisector

a ray that divides an angle into two congruent angles

Coordinate Midpoint Property

(x1+x2/2, y1+y2/2)

parallel lines

coplanar lines that do not intersect

skew lines

non-coplanar lines that do not intersect

perpendicular lines

two lines that intersect to form right angles (90º)

complementary angles

2 angles (the measurement) which add up to 90º

supplementary angles

2 angles (the measurement) which adds up to 180º

vertical angles

when 2 lines intersect a pair on non-adjacent angles

linear pairs

2 adjacent angles that form a line

polygon

A closed figure made up of line segments on the same plane

vertex (vertices)

A point where two or more straight lines meet.

diagonal of a polygon

a line segment that connects two non-consecutive vertices (of a polygon)

convex

has all diagonals (of a polygon) inside

concave

not all diagonals are inside the polygon

equilateral

all sides are equal in length

equiangular polygon

all angles are congruent

regular polygon

a polygon that is both equilateral and equiangular