48 terms

# Geometry Terms

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Acute Triangle
A triangle with three acute angles
Acute Angle
an angle that measures less than 90 degrees
Angle
two rays with a common endpoint, called the vertex
center of rotation
the fixed point a figure is rotated on during a rotation
collinear
points that lie on the same line
complementary angles
Two angles whose sum is 90 degrees
Congruent angles
Angles that have the same measure
congruent figures
figures that have the same size and shape
congruent segments
Segments that have the same length
degrees
a unit for measuring angles
equilateral triangle
A triangle with 3 congruent sides
exterior angles
angles on the outside of parallel lines when cut by a transversal
image
result of a transformation of a point,line or plane
interior angles
angles on the inside of the parallel lines when cut by a transversal
intersecting lines
two lines that share exactly one point
isosceles triangle
A triangle with at least two congruent sides
line
a series of points that extends in opposite directions without end
line of reflection
The line over which a figure is reflected.
line of symmetry
A line that divides a figure into two halves that are mirror images of each other.
line symmetry
if you can draw a line throughit so that the 2 sides are mirror images of each other
obtuse angle
An angle that measures more than 90 degrees but less than 180 degrees
obtuse triangle
a triangle with one obtuse angle
parallel lines
lines in the same plane that never intersect
parallelogram
A quadrilateral with both pairs of opposite sides parallel
perpendicular lines
Lines that intersect to form right angles
plane
A flat surface that extends without end in all directions
point
a location in space that has no size
polygon
Three or more line segments in a plane that forms a closed figure. The line segments never cross but meet at their endpoints.
A polygon with four sides
ray
a part of a line that begins at a point and continues without end in one direction
rectangle
a parallelogram with four right angles
reflection
A transformation that "flips" a figure over a mirror or reflection line.
rhombus
a parallelogram with four congruent sides
right angle
an angle that measures 90 degrees
right triangle
a triangle with one right angle
rotation
A transformation that turns a figure about a fixed point at a given angle and a given direction.
scalene triangle
a triangle with no congruent sides
segment
part of a line with two end points
similar figures
Figures that have the same shape but different sizes; their sides are proportional, while their corresponding angles are equal
skew lines
lines that lie in different planes. they are neither parallel or intersecting
square
A parallelogram with four congruent sides and four right angles
straight angle
an angle that measures 180 degrees
supplementary angles
two angles whose measures have a sum of 180 degrees
translation
A transformation that "slides" each point of a figure the same distance in the same direction.
transversal
A line that intersects two or more lines.
trapezoid
a quadrilateral with exactly one pair of parallel sides
vertex
the point of intersection of the two rays that form the sides of the angle
vertical angles
angles formed by two intersecting lines. Vertical angles are equal