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What is a Parallelogram?
What is a parallelogram?
Summary
- The parallelogram has four sides, which means it's a quadrilateral
- The opposite sides of this parallelogram are parallel and congruent
- Line segment AD is opposite to BC, and line segment AB is opposite to DC
- The equals sign with a little squiggly line above it stands for congruence
- The dash marks on the sides mean that they are the same length
- Angle A is opposite to C, and angle D is opposite to B

Notes
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- Line segment AD is opposite to BC, and line segment AB is opposite to DC
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- Line segment AD is opposite to BC, and line segment AB is opposite to DC
- 'Congruent' means that they are the same length
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- Angle A is opposite to C, and angle D is opposite to B
- Opposite angles are angles that are across from each other
- 'Congruent' means they have the same measurement
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- A quadrilateral is a 4-sided polygon
- 'Congruent' means that opposite sides are the same length
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- Rectangles have four right angles
- The little boxes on the angles in the diagram means they are right angles
- All parallelograms have opposite sides that are parallel and congruent
- All rectangles are parallelograms, but not all parallelograms are rectangles
- Some parallelograms don't have 4 right angles, so they are not rectangles
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- A rhombus has four congruent sides
- All parallelograms have opposite sides that are parallel and congruent
- Since all sides are congruent in a rhombus, opposite sides are congruent
- Every rhombus is a parallelogram, but not every parallelogram is a rhombus
- Not all parallelograms have all four sides congruent, so they are not rhombuses
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- A square has four right angles and four congruent sides
- The little boxes on the angles in the diagram means they are right angles
- All parallelograms have opposite sides that are parallel and congruent
- Since all sides are congruent in a square, opposite sides are congruent
- All squares are parallelograms, but not all parallelograms are squares
- Not all parallelograms have all four sides congruent or four right angles, so they are not squares
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- A trapezoid has exactly one pair of parallel sides
- All parallelograms have opposite sides that are parallel and congruent
- Since a trapezoid only has one pair of parallel sides instead of two, trapezoids are not parallelograms