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# How many sides are there in a parallelogram?

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A parallelogram is a two-dimensional rhomboid or quadrilateral with four sides. The four sides, or edges, consist of two pairs, each with the opposite side parallel and congruent. The two pairs of consecutive angles, or vertices, in a parallelogram are supplementary, which means that the sum of the angles in each consecutive pair is 180 degrees.

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The perimeter of a parallelogram is obtained through the formula 2(a + b), in which "a" and "b" represent the lengths of the opposite and congruent sides. The area of a parallelogram is determined by multiplying the length of its base by its height, the same formula which is used for a finding the area of a rectangle. This is because a parallelogram can be rearranged into a rectangle by dividing it into a right triangle and a trapezoid and then moving the right triangle over to the other side.

Most of the theorems governing parallelograms are from Euclidean geometry and date back to more than 2,000 years ago. Euclid of Alexandria's major work, "Elements," contains the text of what was used as the standard basis of first-year geometry. Euclid's geometry theorems serve as fundamental exercises in mathematical deduction and were studied by individuals such as Abraham Lincoln as a means of heightening their overall powers of reasoning.

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## Related Questions

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A polygon with four sides and four angles is called a quadrilateral. Quadrilaterals are two-dimensional, closed shapes with angle measurements that add up to 360 degrees.

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By its very definition, a quadrilateral is merely a shape with four sides and four vertices or corners. The prefix "quad-" simply means "four" and lateral means "sides," so the name explicitly lays out its meaning.

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A kite is a quadrilateral, a shape with four straight, flat sides, that has two pairs of sides where the two adjacent sides, the ones that meet, are equal in length. The two angles in a kite where the sides with different measurements meet are identical. The other two angles may or may not be identical.