### Rectangle, Composite Figure, and Triangle Notes

```Notes
Name
Unit 5
Area of Rectangles and
Irregular Figures
Find the area of a rectangle that is
8 inches long and 3 inches wide.
A. Use Counting
Draw the rectangle on graph paper. Let
each square represent 1 square inch.
Count the squares inside the rectangle.
There are 24 squares, so the area is
24 sq in.
B. Use a Formula
Use the formula for area. To find area,
multiply length times width.
A=ℓ×w
A=8×3
A = 24
ℓ = length, w = width
ℓ = 8, w = 3
The area of the rectangle is 24 sq in.
A path around a garden measures 8 ft by
7 ft. The garden measures 4 ft by 3 ft.
What is the area of the path?
A. Use Counting
Draw the figure on graph paper. Let each
square represent 1 square foot.
Count the squares in the path only. There
are 44 squares, so the area is 44 sq ft.
B. Use a Formula
Find the area of the path and the garden
together. Then subtract the area of the garden.
Path:
Display:
A=ℓ×w
A=ℓ×w
A=8×7
A=4×3
A = 56 sq ft
A = 12 sq ft
56 − 12 = 44, so the area is 44 sq ft.
Find the area of each figure.
1.
2.
4. Suppose a rectangular path around a rectangular garden
measures 4 meters by 7 meters. The garden measures
3 meters by 6 meters. What is the area of the path?
3.
Name
Area of Parallelograms
and Triangles
Find the area of this parallelogram.
Find the area of this triangle.
Use the formula A = bh.
Use the formula A =
A=8×6
A=
A = 48 sq in.
The area of the parallelogram is 48 sq in.
1
2
1
2
bh.
× 10 × 8
A=5×8
A = 40 cm2
The area of the triangle is 40 cm2.
Find the area of each parallelogram or triangle.
1.
2.
3. Triangle: b = 6 ft, h = 9 ft
4. Parallelogram: b = 18 m, h = 13 m
5. Triangle: b = 20 in., h = 9 in.
6. Writing to Explain Tony says he does not have enough
information to find the area of this parallelogram.
Is he correct? Explain.
Massachusetts Comprehensive Assessment System
CONVERSIONS
1 cup ! 8 fluid ounces
1 pint ! 2 cups
1 quart ! 2 pints
1 gallon ! 4 quarts
1 gallon ! 3.785 liters
1 liter ! 0.264 gallon
1 inch ! 2.54 centimeters
1 meter ! 39.37 inches
1 mile ! 5280 feet
1 mile ! 1760 yards
1 mile ! 1.609 kilometers
1 kilometer ! 0.62 mile
1 pound ! 16 ounces
1 pound ! 0.454 kilogram
1 kilogram ! 2.2 pounds
1 ton ! 2000 pounds
1 liter ! 1000 cubic centimeters
AREA (A) FORMULAS
VOLUME (V) FORMULAS
square . . . . . . . . . . . A ! s 2
right rectangular prism . . . . . V ! lwh
(l ! length; w ! width; h ! height)
rectangle . . . . . . . . . A ! bh
OR
A ! lw
parallelogram . . . . . A ! bh
triangle . . . . . . . . . . A ! 1 bh
2
(b ! length of base; h ! height)
circle. . . . . . . . . . . . A ! πr2