This document defines and classifies different types of quadrilaterals: a parallelogram has two pairs of parallel sides, a trapezoid has one pair of parallel sides, a trapezium has no parallel sides, and a rhombus is a parallelogram where all sides are equal.

1. inv#6.notebook March 11, 2013
Investigation #6:
*quadrilateral - a 4-sided polygon
*parallelogram - a quadrilateral with 2 pairs of parallel sides
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*trapezoid - a quadrilateral with only 1 pair of parallel sides
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2. inv#6.notebook March 11, 2013
*trapezium - a quadrilateral with no pairs of parallel sides
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*rhombus - a parallelogram with all sides equal
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