26 terms

# 6th grade math chapter 8

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point
marks a location; has no size
line
extends in both directions forever
plane
a flat surface that extends forever
ray
A part of a line, with one endpoint, that continues without end in one direction
line segment
A part of a line with two endpoints
congruent
Having the same size and shape
intersecting lines
lines that cross at exactly one point
perpendicular lines
Lines that intersect to form right angles
parallel lines
lines that never intersect
angle
A figure formed by two rays with a common endpoint
vertex
The common endpoint of an angle
degree
A unit of measurement of angles
right angle
an angle that measures 90 degrees
acute angle
an angle that measures less than 90 degrees
obtuse angle
An angle that measures more than 90 degrees but less than 180 degrees
straight angle
an angle that measures 180 degrees
vertical angles
A pair of opposite congruent angles formed by intersecting lines; vertical angles are congruent
supplementary angles
Two angles whose sum is 180 degrees
complementary angles
Two angles whose sum is 90 degrees
right triangle
a triangle with one right angle
triangle
a figure with 3 sides and 3 angles; sum of its angles is always 180 degrees
acute triangle
A triangle with 3 acute angles
obtuse triangle
a triangle with one obtuse angle
scalene triangle
a triangle with no congruent sides
isosceles triangle
a triangle with at least two congruent sides
equilateral triangle
A triangle with three congruent sides