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Polygon

a closed figure with straight lines

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Triangle

a polygon with 3 sides

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Angles of a triangle

the sum of the measures of the angles of any triangle is 180 degrees

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Scalene

a polygon with no sides equal

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Isosceles

a polygon with 2 sides equal

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Equilateral

a polygon with all sides equal

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Acute triangle

a triangle with all 3 angles less than 90 degrees

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Equianagular

a polygon with all angles equal

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Obtuse triangle

a triangle with one obtuse angle

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Right triangle

a triangle with one right angle

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Quadrilateral

a polygon with 4 sides

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Parallelogram

a quadrilateral with opposite sides parallel

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Rectangle

a parallelogram with 4 right angles

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Square

a rectangle with all sides congruent

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Rhombus

a parallelogram with all sides congruent

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Trapezoid

a quadrilateral with one pair of parallel sides

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Kite

a quadrilateral with neighboring sides congruent

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Pentagon

a polygon with 5 sides

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Hexagon

a polygon with 6 sides

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Heptagon

a polygon with 7 sides

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Octagon

a polygon with 8 sides

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Nonagon

a polygon with 9 sides

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Decagon

a polygon with 10 sides

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Dodecagon

a polygon with 12 sides

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Icosagon

a polygon with 20 sides

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Congruent polygons

polygons that are the same size and same shape

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