4 5 Perimeter and Area Perimeter is the

4. 5 – Perimeter and Area

Perimeter is the distance around the OUTSIDE of a shape. To find the perimeter, simply ADD the lengths of each SIDE. Perimeter is always measured in LINEAR units.

Area is the number of square units that cover the INSIDE of the shape. To find the area, we will usually be MULTIPLYING the dimensions of the shape, and possibly some other CONSTANT as well.

Example 1: Find the perimeter and the area of the following shapes, where each block represents 1 square foot. A. ) P = A = B. ) 16 ft. P = 12 ft. 15 sq. ft A = 9 sq. ft

Example 2 – Complete the table below to find the formula for the perimeter of a rectangle. Length Width Perimeter

Area and Fixed Perimeter Suppose Rick has 12 yards of fencing to build a pen for his dog. Consider all possible integral dimensions for the pen. Complete the table below and make a generalization about the shape of a rectangular pen with fixed perimeter and greatest possible area.

Fixed Perimeter Length Width Area 12 yd. 1 yd. 5 sq. yd. 12 yd. 4 yd. sq. yd. 12 yd. yd. yd. sq. yd. GENERALIZATION: The shape of a rectangle with fixed perimeter and the greatest possible area is a SQUARE.

Perimeter and Fixed Area Suppose Rick has needs to make sure his dog has 36 square yards of space in its pen. Consider all possible integral dimensions for the pen. Complete the table below and make a generalization about the shape of a rectangular pen with fixed area and smallest possible perimeter.

Area Length Width Perimeter 36 sq. yd. 1 yd. 36 yd. 74 yd. 36 sq. yd. 2 yd. 18 yd. 36 sq. yd. 3 yd. yd. yd. 36 sq. yd. yd. yd. GENERALIZATION: The shape of a rectangle with fixed area and the smallest possible perimeter is a SQUARE.

Homework : Section 4. 5 pages 236 -238 #’s 8 -40 EVEN