25 terms

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point
indicates location in space and has no size.
line
a series of infinite points that extends forever in opposite directions.
plane
a flat surface that extends infinately in all directions
parallel lines
two lines in the same plane that never intersect
angle
formed by two rays with a common endpoint called the vertex
right angle
an angle whose measure is exactly 90 degrees
straight angle
an angle whose measure is exactly 180 degrees, an angle that forms a straight line
vertex
where two rays have a common end point
ray
a part of a line with one endpoint and all the points of the line on one side of the endpoint
line segment
a finite portion of a line.
intersecting lines
two lines in the same plane that share a single point
skew lines
lines that do not exist in the same plane. They are neither intersecting or parallel
acute angle
an angle whose measure is less than 90 degrees
obtuse angle
an angle whose measure is greater than 90 degrees and less than 180 degrees
complementary angles
two angles whose combined measures add up to 90 degrees
two angles that share a common ray (vertex and side) but have no interior points in common
vertical angles
two angles that are opposite each other when two lines intersect. also known as opposite angles
acute triangle
a triangle with 3 acute angles
obtuse triangle
a triangle with one obtuse angle
isosceles triangle
a triangle with at least 2 congruent sides
supplementary angles
two angles whose combined measures add to 180 degrees
congruent
identical, equal
right triangle
a triangle with one right angle
scalene triangle
a triangle with sides of different lengths
equilateral triangle
a triangle with 3 congruent sides