###
acute angle

An angle less than 90 degrees

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right angle

an angle that measures 90 degrees

###
obtuse angle

An angle more than 90 degrees

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complementary angles

two angles whose measures have a sum of 90 degrees

###
supplementary angles

two angles whose measures have a sum of 180 degrees

###
congruent

Sides are congruent, angles are congruent

###
vertical angles

a pair of opposite congruent angles formed by intersecting lines

###
adjacent angles

two angles that share a common vertex and side, but have no common interior points

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alternate interior pair

angles which are on opposite sides of the transversal and inside of the parallel lines

###
corresponding angles

are angles which are in a similar position in relation to the transversal and the line that it intersects

###
parallel lines

lines that never intersect

###
perpendicular lines

Two lines that intersect to form right angles

###
equilateral triangle

a triangle with three congruent sides

###
isosceles triangle

a triangle with two congruent sides

###
scalene triangle

a triangle with no congruent sides

###
acute triangle

A triangle with three acute angles

###
obtuse triangle

a triangle with one obtuse angle

###
right triangle

a triangle with 1 right angle

###
rhombus

a parallelogram with 4 congruent sides

###
quadrilateral

a four-sided polygon

###
parallelogram

A quadrilateral with two pairs of parallel sides

###
trapezoid

a quadrilateral with exactly one pair of parallel sides

###
square

a parallelogram with four congruent sides and four right angles

###
rectangle

A parallelogram with 4 right angles

###
polygons

a closed plane figure made up of line segments

###
pentagon

a five-sided polygon

###
hexagon

a six-sided polygon

###
heptagon

a seven-sided polygon

###
octagon

an eight-sided polygon

###
nonagon

a nine-sided polygon

###
decagon

a ten sided polygon

###
regular polygon

a polygon with congruent sides and angles

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