1.1 Points, Lines and Planes
Undefined Terms – Words/items that are only explained using
examples or descriptions.
Collinear – Points that lie on the same line.
Coplanar – Points that lie on the same plane.
Intersection – The set of points that two or more geometric
figures have in common.
Space – A boundless, three-dimensional set of all points. Can
contain lines and planes.
1.2 Linear Measure
Line Segment – A measurable part of a line that consists of two
points, called endpoints, and all of the points between them.
Congruent Segments – Segments that have the same measure.
Constructions – A method of creating geometric figures without the
benefit of measuring tools.
Generally a compass and straightedge are used.
Precision – A clustering of a group of measurements.
Depends on the smallest unit of measure available on
measuring tool.
Accuracy – How close a measured value comes to the actual or
desired value.
1.3 Distance and Midpoints
Distance – The length of the segment between two points.
Distance Formula
Midpoint – The point halfway between the endpoints of a
segment.
Midpoint Formula
Segment Bisector – Any segment, line, or plane that
intersects a segment at its midpoint.
1.4 Angle Measure
Ray – A part of a line that has one endpoint and extends
indefinitely in one direction.
Opposite Rays – Two rays on the same line that share a
common endpoint.
Angle – An object formed by two noncollinear rays that have
a common endpoint.
Sides – The rays that make up the angle.
Vertex – The common endpoint of an angle.
Degree – The unit used to measure angles. Equal to 1/360th
of a turn around a circle.
Angle Bisector – A ray that divides an angle into two
congruent angles.
1.5 Angle Relationships
Perpendicular – Lines, segments, or rays that form right
angles.
1.6 Two Dimensional Figures
Concave – If any of the lines that contain each side is extended and
goes through the inside.
Convex – If none of the lines that contain each side is extended and
never pass through the interior.
Names of Polygons
Number of Sides
3
4
5
6
7
8
9
10
12
N
Type (Name) of Polygon
Triangle
Quadrilateral
Pentagon
Hexagon
Heptagon
Octagon
Nonagon
Decagon
Dodecagon
n-gon
Equilateral, Equiangular, and Regular
Equilateral – All sides are equal.
Equiangular – All angles are equal.
Regular – All sides and angles are equal. It would be both
Equilateral and Equiangular.
Perimeter – The sum of the lengths of the sides of a polygon.
Circumference – The distance around a circle.
Area – The number of square units needed to cover a surface.
1.7 Three-Dimensional Figures
Polyhedron – A solid with all flat surfaces that enclose a single
region of space.
Face – The polygons that make up the flat surface.
Edge – The line segments where the faces intersect.
Vertices – The point where three or more edges intersect.
Regular Polyhedron – A polyhedron with all faces being regular
congruent polygons.
Surface Area – A two-dimensional measurement of the surface of a
solid figure.
Volume – The measure of the amount of space enclosed by a solid
figure.