PERIMETER: THE DISTANCE AROUND A FIGURE

ExampleWhat is the perimeter of the figure below?12 ft

9 ft

6 ft

6 ft

18 ft

15 ft

12 ft+ 9 ft+ 6 ft+ 6 ft

+ 18 ft+ 15 ft

66 ft

FORMULA: AN EQUATION THAT SHOWS HOW CERTAIN QUANTITIES ARE RELATED.Some figures have special characteristics.

For example, because the opposite sides of a rectangle have the same length, we can use a formula to find its perimeter.

PERIMETER OF A RECTANGLE: P = 2l + 2wExample: What is the perimeter of the

rectangle below?

9 m

5 m

P = 2l + 2wP = 2(9) + 2(5)P = 18 + 10P = 28

The perimeter is 28 m.

AREA: THE NUMBER OF SQUARE UNITS NEEDED TO COVER ITS SURFACE.

The area of a rectangle can be found by dividing it into 1x1 squares of whatever unit we’re using

AREA OF A RECTANGLE: A = lw

5 m

4 m

ExampleFind the area of the rectangle

Find the area of a rectangle with a length of 8.2 meters and a width of 2.4 meters

14 in

10 inThe area is 140 square inches

19.68 m2

The opposite sides of a parallelogram also have the same length. The area of a parallelogram is closely related to the area of a rectangle.

AREA OF A PARALLELOGRAM: A = bh

height

base

ExampleFind the area of the parallelogram

Find the area of a parallelogram with a height of 6 feet and a base of 8 feet

5.2 in

4 mThe area is 20.8 square meters

48 ft2

4.3 m

Some math problems can be solved by using a formula. Others can be solved by a problem-solving strategy like finding a pattern (section 1) or making a model. No matter the problem, you can always use a four-step plan.1. Explore the problem2. Plan the solution3. Solve the problem4. Examine the solution

Example Julia wants to paint two rectangular walls of

her bedroom. One bedroom wall is 15 feet long and 8 feet high. The other wall is 12 feet long and 8 feet high. She wants to put two coats of paint on the walls. She knows 1 gallon of paint will cover about 350 square feet of surface. Will one gallon of paint be enough? Wall one is 15 by 8 feet. What is the area? Wall two is 12 by 8 feet. What is the area? How much paint is needed to give two coats? Can Julia paint both walls twice?

120 ft2

96 ft2

432 ft2

No

AssignmentWorksheet