1. Cell phone use is prohibited.
Students:
Today is a red light day.
Cell phone use is prohibited.
This is your warning.

2. 1) Find the area and perimeter of the rectangle
whose base = 8 mm and height = 9 mm.
P = 2(8 mm) + 2(9 mm)
= 16 mm + 18 mm
= 34 mm
A = (8 mm) • (9 mm)
= 72 mm2
2) Find the area and perimeter of the square
whose side = 12 yd.
P = 4 • s
= 4 • 12 yd
= 48 yd
A = (12 yd)2
= 144 yd2
3) Find the missing side and perimeter of the
rectangle whose base = 6 cm and area = 42 cm2.
42 cm2 = (6 cm) • (height)
7 cm = height
P = 2(6 cm) + 2(7 cm)
= 12 cm + 14 cm
= 26 cm

3. 17.02 Area of a Parallelogram

4. The base and height meet to form a right angle.
Height (h)
Height (h)
Base (b)
The area formula of a parallelogram is A = b • h, but the height is not the side of the parallelogram.
The base and height meet to form a right angle.
The height may be a segment inside a figure
or may be a segment outside a figure.
or may be a side like a rectangle.
The height may also be called an altitude.

5. Find the area. A = b • h A = 9 cm • 3 cm A = 8 m • 7 m A = 27 cm2
b = 12 in , h = 8 in
b = 6 yd , h = 4 yd
A = 12 in • 8 in
A = 6 yd • 4 yd
A = 96 in2
A = 24 yd2

6. Find the missing base or height.
To find the height given its area, replace the variables in the formula with their numbers and solve.
Find the missing base or height.
b = 6 m and A = 72 m2
h = 8 cm and A = 144 cm2
A = b • h
A = b • h
72 m2 = 6 m • h
144 cm2 = b • 8 cm
12 m = h
18 cm = b

7. The area formula of a rhombus
A = ½ • d1 • d2
Find the area d1 d2
d1 = 8
d2 = 12
A = ½ • d1 • d2
= ½ • 8 • 12
= ½ • 96
= 48

8. To find the area and perimeter of a parallelogram given the base and height, use the Pythagorean Theorem to find missing side.
a2 + b2 = c2
(x)2 = (6)2 + (8)2
8 m
x m
x2 =
x2 = 100
12 m
6 m
x = 10
A = b • h
= 12 m • 8 m
= 96 m2
P = 2(12 m) + 2(10 m)
= 24 m + 20 m
= 44 m