Calculating Areas for Parallelograms and Rectangles.

Maybe you know how to find the area of a square, or a rectangle; but what about when you are required to find the area of a rectangle when they give you one side in terms of the other side, and you realize that the simple formula won't be enough, and you will need to factor a quadratic equation? What about when you have to find the area of a square when you know the length of one of the diagonals, and you realize you need to apply special right triangles?

All along this lesson, you will work examples that illustrate very similar cases like the ones above described. You will be enabled to solve problems on your own, and have them instantly graded. The lesson is a great opportunity to become proficient in finding areas for parallelograms and rectangles!

Lesson's Content

Lesson's Glossary

Area
The amount of space taken up in a plane by a figure.

Parallelogram
Any quadrilateral with two pairs of opposite sides parallel.

Polygon
It is a closed plane figure with a least three straight segments as sides.

Perimeter of a polygon
The sum of the lengths of the sides of the polygon.

Quadrilateral
A four-sided polygon.

Rectangle
Any parallelogram that has 4 right angles.

Interactive Geometric Applets: Relevant Theorems.

In a parallelogram you have properties which allow you solving for angles, and sides

in the parallelogram. For example: Opposite sides are parallel and congruent, opposite

angles are congruent, consecutive angles are supplementary, and diagonals bisect each other.

Check this interactive geometric applet to review these properties before calculating areas.

A rectangle is one parallelogram which has all angles right and congruent, with

congruent diagonals, which bisect forming 4 congruent segments. It has opposite sides

parallel and congruent. Interact with this great geometric applet in order to review

all these properties, and use them in calculating areas for rectangles.

Vocabulary Puzzle Interactive

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