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### Unit 5: Lesson 4

Topic D: Drawing, analysis, and classification of two-dimensional shapes

Learn about the properties of quadrilaterals, parallelograms, trapezoids, rhombuses, rectangles, and squares. Created by Sal Khan and Monterey Institute for Technology and Education.

## Want to join the conversation?

• In i realized that a rectangle cannot be a square, however a square can be a rectangle. Is this right?
• "In i realized that a rectangle cannot be a square, however a square can be a rectangle. Is this right?" Your statement before your question is not worded correctly. A square is always a rectangle, by definition. However, not all rectangles are squares. A square is the unique case of a rectangle also having 4 sides with the same length.
• a square is not always a retangle however it could be sometimes
• can you vote this up please and thank you

goal: <250
• A shape could have as many as a 10000000 sides right?
• There are shapes such as chilikagon with 1000 sides.
And 3d shapes such as myriagon with 10,000 sides.
There can be shapes liked that with 10000 or so sides but I have not heard of anything like that.
• Which definition of a trapezoid would you guys pick? My choice is at least one pair of parallel. What's yours?
• A 4-sided flat shape with straight sides that has a pair of opposite sides parallel.
• What do the yellow tick marks/tiny lines on each side of the shape indicate?
• The squares on the corners indicate it is a right angle, meaning a 90 degree angle and the lines on the sides i think indicate if that side is parallel with its opposite side.
• Is there any differences between a trapezoid and a trapezium?
Or are they same?
• I don't get how a square is a rectangle but a rectangle isn't a square. They are two different shapes so how can they be the same.
• It's all about the formal definitions of the shapes. A rectangle is a 4-sided figure, with 4 right angles, and 2 sets of parallel lines. A square also fits this definition. A square is all the things a rectangle is, but with the added condition that all the sides need to be the same length.

This makes all squares rectangles, but no rectangles are squares.
(1 vote)
• What's the meaning of #congruent here. Sal uses this word I searched this but it didn't make sense to me. Can someone please explain the meaning of #congruent that Sal uses here?
• “Congruent” means that two things are the same size and shape.

For example:
If you had a circle and a smaller circle, those wouldn’t be congruent because they’re not the same size. If you had a triangle and a square that both had an area of 9 square units, they wouldn’t be congruent because they’re different shapes. If you have two regular hexagons that have side lengths of 3 units, those would be congruent.