CK-12 Geometry-Concepts

http://www.ck12.org Chapter 6. Polygons and Quadrilaterals

6.4 Quadrilaterals that are Parallelograms

Here you’ll learn how to prove that a quadrilateral is a parallelogram.

What if four friends, Geo, Trig, Algie, and Calc were marking out a baseball diamond? Geo is standing at home
plate. Trig is 90 feet away at 3rdbase, Algie is 127.3 feet away at 2ndbase, and Calc is 90 feet away at 1stbase. The
angle at home plate is 90◦, from 1stto 3rdis 90◦. Find the length of the other diagonal and determine if the baseball
diamond is a parallelogram. After completing this Concept, you’ll be able to answer questions like this based on
your knowledge of parallelograms.

Watch This

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/52570

CK-12 Foundation: Chapter6QuadrilateralsthatareParallelogramsA

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/10321

Khan Academy: Opposite Sides of a Parallelogram Congruent