Areas of Squares, Rectangles, &

Parallelograms

Objective: TLW find perimeters and areas of squares, rectangles, and parallelograms. TLW utilize points on a coordinate plane determine whether the image is a parallelogram.

RECAP: Squares and Rectangles

Ex. s + s + s + s = 4s 6 + 6 + 6 + 6 = 24 ft

Perimeter: P = 4s Perimeter: P =2l + 2 w

Ex. l + w + l + w = (l +w) + (l + w) = (l + l) + (w + w) = 2l + 2w

14 + 8 + 14 + 8 = 2(14) + 2(8) = 40 inches

How does perimeter tie to area?

Let’s focus on the Square ….

We know each side is 6 ft., … so what if we take squares

where each side is 1 ft. and lay it over top of our square?

What did we just do?

Count the Blocks … what is our area

formula?

Area = s2

Area = (6)2

= 6 ft. 6 ft. = 36 ft.2

Area = l w

Area = (14 in.) (8 in.) = 112 in.2

What does this have to do with the perimeter and

area of a parallelogram??

Let’s Do an Experiment!

Take the rectangle, ruler, and scissors on your desk and do the following: Draw a straight line connecting a vertex to a

point on one of your length sides. Ex:

Now cut along that line!

Let’s Do an Experiment!

Now what are we going to do with the triangle?

Exactly! We’re going to place it on the other side of the “rectangle” and tape the two sides together.

Now, take your ruler and measure each side … Make a Conjecture! Does this have anything to do with the

perimeter and area formulas that we discussed earlier???

Perimeter & Area of a:

Parallelogram Perimeter of a

parallelogram is the sum of all of the measures of its sides. Example: s + s + s +

s = P

But what about the area?

What formula can we create from this diagram?

h

b

Area of a Parallelogram

If a parallelogram has an area of A square units, a base of b units, and a height of h units, then: A = b h