Geometry Basics Flashcards
(24 cards)
adjacent angles
two coplanar angles with a common side, a common vertex, and no common interior points
angle
two rays with a common endpoint; named by its vertex
angle bisector
a ray (or segment of a ray) that divides an angle into two congruent angles
collinear points
points that lie on the same line
complementary angles
two angles whose measures have a sum of 90°
congruent angles
- angles with the same measure
- on a figure this will be shown with arcs of the same kind
congruent segments
- two segments which have the same length; symbol for congruence is ≅
- on a figure this will be shown with hatch (tick) marks of the same kind
coplanar
points and lines that lie in the same plane
line
- a straight path that extends in two opposite directions without end (arrows on both ends) and has no thickness
- named by any two points on the line (with a small line above them)
linear pair
- a pair of adjacent angles whose uncommon sides are opposite rays
- forms a straight angle
midpoint
a point that divides a segment into two congruent segments
parallel lines
- coplanar lines that do not intersect
- symbol is ||
perpendicular lines
lines that intersect at right angles; symbol is ⊥
plane
- a flat surface that extends without end and has no thickness
- contains infinitely many points and lines;
- named by a capital letter (usually script) or by at least 3 points in the plane that do not all lie on the same line
point
- indicates a location and has no size; represented by a dot
- named by a capital letter
postulate/axiom
an accepted statement of fact
ray
- part of a line that consists of one endpoint and all the points of the line on one side of the endpoint (arrow on one end)
- named by its endpoint and another point on the ray (the first letter must be the endpoint) with a small ray above them
segment
- part of a line that consists of two endpoints and all points between them
- named by its endpoints with a small segment above them
skew
lines or segments that do not intersect but are also in different planes
straight angle
measure is 180°
supplementary angles
two angles whose measures have a sum of 180°
vertex
the shared endpoint of the two rays that form an angle
vertical angles
- two angles whose sides are opposite rays
- formed when two lines intersect at one point
- congruent
undefined terms
basic ideas that are used to build the definitions of all other figures in geometry (line, point, plane)
