6.3. Parallelograms http://www.ck12.org
6.3 Parallelograms
Here you’ll learn what a parallelogram is and how to apply theorems about its sides, angles, and diagonals.
What if a college wanted to build two walkways through a parallelogram-shaped courtyard between two buildings?
The walkways would be 50 feet and 68 feet long and would be built on the diagonals of the parallelogram with
a fountain where they intersect. Where would the fountain be? After completing this Concept, you’ll be able to
answer questions like this by applying your knowledge of parallelograms.
Watch This
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Click image to the left for more content.CK-12 Foundation: Chapter6ParallelogramsA
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Click image to the left for more content.Brightstorm:Parallelogram Properties
Guidance
Aparallelogramis a quadrilateral with two pairs of parallel sides. Here are some examples:
Notice that each pair of sides is marked parallel. As is the case with the rectangle and square, recall that two lines
are parallel when they are perpendicular to the same line. Once we know that a quadrilateral is a parallelogram, we
can discover some additional properties.
Investigation: Properties of Parallelograms
Tools Needed: Paper, pencil, ruler, protractor
- Draw a set of parallel lines by placing your ruler on the paper and drawing a line on either side of it. Make
your lines 3 inches long. - Rotate the ruler and repeat this so that you have a parallelogram. Your second set of parallel lines can be any
length. If you have colored pencils, outline the parallelogram in another color. - Measure the four interior angles of the parallelogram as well as the length of each side. Can you conclude
anything about parallelograms, other than opposite sides are parallel?