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Square

4 equal sides. 90 degree angles.

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Rectangle

quadrilateral. 90 degree angles.

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Quadrilateral

4-sided polygon

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Perimeter

distance around a figure

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Area

number of square units it takes to cover a figure

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Right Angle

90 degree angle

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Acute Triangle

3-sided polygon, each angle is less than 90 degrees

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Obtuse triangle

3-sided polygon, 1 angle greater than 90 degrees

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Right Triangle

3-sided polygon. One 90 degree angle.

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Isosceles Triangle

3-sided polygon. 2 congruent sides.

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Equilateral Triangle

3-sided polygon. 3 congruent sides. 3 60 degree angles.

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Scalene Triangle

3-sided polygon. No congruent sides

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parallelogram

4-sided quadrilateral. 2 pairs of parallel lines

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parallel lines

lines that will never intersect

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trapezoid

4-sided quadrilateral. 1 pair of parallel lines

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congruent

same size, same shape

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rhombus

4-sided polygon with all congruent sides

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segment

section of a line between two endpoints

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vertex or vericies

the point where 2 lines meet

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polygon

many-sided figure, closed, straight line segment

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regular polygon

polygon with congruent sides and congruent angles

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irregular polygon

polygon without all congruent sides

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straight angle

angle measuring 180 degrees

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complementary angles

angles whose sum equals 90 degrees

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Supplementary angles

angles whose sum equals 180 degrees

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regular polygon

a polygon with congruent sides and congruent angles

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acute angle

an angle less than 90 degrees

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obtuse angle

an angle more than 90 degrees

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intersecting lines

lines that cross

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perpendicular lines

lines that intersect and form 90 degree angles where they cross

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angle

two rays that start from the same endpoint

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