Math 6 Honors Periods 6 & 7 (Tuesday )

Areas of Rectangles and Parallelograms 10-1

In Chapter 4 (so long ago) we measured lengths of segments and found perimeters of various polygons. Now we will measure the part of the plane enclosed by a polygon. We call this measure the area of the polygon.

In the metric system the unit area often use is the square centimeter. cm²

Notice that the area of each rectangle is the product of the lengths of the two consecutive sides. These sides are called the length and the width of the rectangle The length names the longer side and the width names the shorter side. These sides are also named the base and height.

Formula

Area of rectangle = length · width

A= lw

The length and the width of the rectangle are called its dimensions

In the case of a parallelogram, we may consider either pair of parallel sides to the bases. (the word base is also used to denote the length of the base) the height is the perpendicular distance between the bases.

Formula

Area of parallelogram = base · height

A= bh

The unit areas used are square meters (m²), square millimeters (mm²) and square centimeters (cm²). For very large regions, such as the State of California, or entire countries (Canada), we could use square kilometers (km²)

Sometimes we work with an unspecified unit of length. Then the unit of area is simply called a square unit. It is vital, however, that you indicate the area is in square units.