###
isosceles triangle

a triangle with two equal sides

###
vertex

The common endpoint of an angle

###
obtuse triangle

a triangle with one obtuse angle

###
right triangle

a triangle with one right angle

###
scalene triangle

a triangle with no two sides of equal length

###
equilateral triangle

a triangle with three equal sides

###
straight angle

an angle that measures 180 degrees

###
obtuse angle

An angle more than 90 degrees

###
right angle

an angle that measures 90 degrees

###
angle

two rays with a common endpoint

###
acute angle

An angle less than 90 degrees

###
plane

An endless flat surface

###
line segment

part of a line with two endpoints

###
point

An exact location in space

###
intersecting lines

lines that cross at one point

###
ray

Part of a line that has one endpoint and extends forever in one direction.

###
line

A straight path of points that goes on forever in two directions

###
perpendicular lines

Two lines that intersect to form right angles

###
parallel lines

Lines in the same plane that do not intersect

###
Skew lines

Lines that do not intersect, are not parallel, and are not in the same plane

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