Name
width
width
length
length
Metric Units of Measurement
depth
U.S. Units of Measurement
Length / Distance
(linear)
Length / Distance (linear)
1 centimeter (cm)
10 millimeters (mm)
1 inch (in)
1 meter (m)
100 centimeters
1 foot (ft)
12 inches
1 kilometer (km)
1000 meters
1 yard (yd)
3 feet
Square Measure
(area; 2-D)
1 mile (mi)
1,760 yards
1 square cm (cm²)
100 mm²
Square Measure
(area; 2-D)
1 square meter (m²)
10,000 cm²
1 square inch (in²)
1 square kilometer
1,000,000 m²
1 square foot (ft²)
144 in²
1 square yard (yd²) 9 ft²
© 2008 abcteach.com
1 square mile
3,097,600 yd²
Look at the rectangle to the right. Place
your finger on the outline of the rectangle
at the arrow. With your finger, trace the line
all the way around the rectangle, back to
the arrow. That is the perimeter.
Perimeter is the outer border of a two-dimensional figure.
To find the perimeter of any polygon, simply measure all
the sides and add them together.
4
4 square 4
6
2
4
4+4+4+4=16
P=16
1
3
6
3
triangle
3
6+2+6+2=16
P=16
3+3+3=9
P=9
rectangle
2
1
1+1+1+1+1=5
P=5
1
2
2
3
2
© 2008 abcteach.com
pentagon
1
2
Irregular shapes work the same way.
2+2+2+1+2+3=12
P=12
1
1
Look at the triangle to the right. All of the red
that you see is the area of the triangle.
Area is the space of a 2-dimensional surface that is enclosed
within a boundary. We use formulas to find the area of a shape.
It is easy to see how this works by looking at the formula of a
rectangle.
The formula for finding the area of a rectangle is:
A = LW or Area equals Length times Width.
The rectangle to the right is 4 cm long by 3 cm wide.
Use the formula to find the area.
L = 4 and W = 3
3
A=4x3
4 x 3 = 12
A = 12
Write the answer like this: A = 12cm²
4
To see how this works, count the squares inside.
There are 12 small squares. Each square within the rectangle
is 1 square cm. So, the area of the rectangle equals 12 square
centimeters.
inches
© 2008 abcteach.com
RECTANGLE
SQUARE
Area = Length x Width
A = LW
Area = length of a side squared
A = s²
Example:
A=3x2
3x2=6
A = 6 in²
Example:
A = 4²
A=4x4
A = 16
A = 16 cm²
W=
3 in
L= 2 in
s = 4 cm
TRIANGLE
PARALLELOGRAM
Area = Base x Height ÷ 2
A = BH/2
Area = Base x Height
A = BH
Example:
A = (3 x 4) ÷ 2
3 x 4 = 12
12 ÷ 2 = 6
A = 6 cm²
Example:
A=3x4
3 x 4 = 12
A = 12 in²
H=
3 cm
H= 4 in
B= 3 in
B = 4 cm
TRAPEZOID
CIRCLE
Area =
Height x (Base 1 + Base 2) ÷ 2
A = H(B1 + B2)/2
Area = pi x radius squared
Example:
A = 3(2 + 4) ÷ 2
2+4=6
3 x 6 = 18
18 ÷ 2 = 9
A = 9 in²
© 2008 abcteach.com
B2= 4 in
H= 3 in
B1= 2 in
A = r²
Example:
≈ 3.14
A = 3.14 x 2²
3.14 x 4 = 12.56
A = 12.56 cm²
r = 2 cm