What is a parallelogram? First a parallelogram is a quadrilateral, and a polygon which means it is a closed two dimensional figure with four sides. Let's look at the properties that define a parallelogram.
"A" and "B" add to 180 therefore they are supplementary
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Hi Welcome to MooMooMath. Today we are going to talk about parallelograms. Before I look at the properties let’s see where the parallelogram fall in the quadrilateral family. A parallelogram is a four sided polygon which means it is a quadrilateral so it is under the big umbrella of quadrilaterals. So we are looking at the side of the quadrilateral family that are all parallelograms and under parallelograms fall these other figures, a rectangle and a rhombus and a square. Let’s look at the properties of just a parallelogram, a parallelogram has several properties. A definition of a parallelogram is that the opposite sides AT and MH would be parallel to each other and we will represent that with a symbol of an arrow, and MA and HT are also parallel Now some other properties are that the opposite angles are congruent meaning that if angle A is 180 degrees the angle opposite it would also be 180 degrees. So measure of angle A and same as the measure of angle H. Also, angle M would be congruent with angle T. The next property is that opposite sides are parallel. So MA is congruent (equal length) to HT and side AT is congruent to MH so they have the same length. So if this side is 5 then the opposite side is 5 and the same with AT and MH so if AT is 8 then MH is 8. Therefore opposite sides of a parallelogram are congruent. Then we have one more property and that is the adjacent angles (angles next to each other) are supplementary which means they add to 180. So if we know this angle is 100 then angle M must be 80.