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27 terms

Geometry Terms

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point
names a location
line
is perfectly straight and extends forever in both directions
plane
is a perfectly flat surface that extends forever in all directions
segment
is the part of a line between two points
ray
is part of a line that starts at one point and extends forever in one direction
angle
is formed by two rays with a common end-point called the vertex.
right angle
an angle that measures 90 degrees
acute angle
an angle that measures more than zero but less than 90 degrees
obtuse angle
an angle that measures more than 90 degrees, but less than 180 degrees
complementary angles
two angles whose measures add to 90 degrees
supplementary angles
two angles whose measures add up to 180 degrees
congruent figures
figures that have the same shape and same size
vertical angles
a pair of opposite congruent angles formed by intersecting lines
Triangle Sum Theorem
states that the measures of the angles in a triangle add up to 180 degrees
acute triangle
has 3 acute angles
right triangle
has one right angle
obtuse triangle
has one obtuse angle
equilateral triangle
has three congruent sides and angles
isosceles triangle
has at least two congruent sides and angles
scalene triangle
has NO congruent sides or angles
polygon
is a closed plane figure formed by three or more sides
regular polygon
a polygon with congruent sides and angles
trapezoid
a quadrilateral with exactly one pair of parallel sides
paralellogram
a quadrilateral that has 2 pairs of parallel sides
rectangle
a parallelogram with four right angles
rhombus
a parallelogram with all side congruent
square
a parallelogram with four right angles and four congruent sides