Cool math .com - The Properties of a Parallelogram (perimeter, area, interior angles, diagonals, lengths of sides)

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The Properties of a Parallelogram
Definitions and formulas for the perimeter of a parallelogram, the area of a parallelogram, properties of the sides and angles of a parallelogram
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perimeter of a parallelogram	area of a parallelogram
properties of the sides and angles of a parallelogram	other properties of the angles of a parallelogram

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The perimeter of a parallelogram:
	To find the perimeter of a parallelogram, just add up all the lengths of the sides: Perimeter = a + b + a + b = 2a + 2b

The area of a parallelogram:
	To find the area of a parallelogram, just multiply the base length (b) times the height (h): Area = b x h
Yeah, that's the formula... But let's check out where it comes from!

Let's cut off a piece and move it...

parallelogram

Now, it's a rectangle!
Area = length x width = b x h

parallelogram

The sides and angles of a parallelogram:

parallelogram

Opposite sides of a parallelogram are the same length (congruent).

Opposite angles of a parallelogram are the same size/measure (congruent.)

Opposite sides of a parallelogram are parallel... Uh... You think that's where it got it's name?

Other properties of the angles of a parallelogram:
	Adjacent sides (ones next to each other) of a parallelogram are supplementary. This means that their measures add up to 180 degrees.