Download Outline 2.6

RCM: Notes 2.6 – Formulas and Problem Solving
General Strategy for Problem Solving
1. Understand the problem
a. Read the problem
b. Choose a variable to represent the unknown value
c. Construct a drawing, whenever possible
2. Translate the problem into an equation
3. Solve the equation
4. Interpret the results – does your solution make sense?
Common Formulas
Area of a rectangle = length  width
A  lw
Simple Interest = Principal  Rate  Time
I  PRT
Perimeter of a triangle = side a + side b + side c
P  a b c
Distance = Rate  Time
d  rt
Volume of a rectangular solid = length  width  height
V  lwh
9
9
Degrees Fahrenheit =
F  C  32
 Degree Celsius + 32
5
5
Example 1
A glacier is a giant mass of rocks and ice that flows down hill like a river. Portage
Glacier in Alaska is about 6 miles, or 31,680 feet long and moves 400 feet per year.
Icebergs are created when the front end of the glacier flows into Portage Lake.
How long does it take for ice at the head (beginning) of the glacier to reach the
lake?
Example 2
The average maximum temperature for January in Algerias, Algeria, is 59°
Fahrenheit. Find the equivalent temperature in degrees Celsius.
Example 3
Charles Pecot can afford enough fencing to enclose a rectangular garden with a
perimeter of 140 feet. If the width of his garden must be 30 feet, find the
length.
Example 4
The length of a rectangular road sign is 2 feet less than three times its width.
Find the dimensions if the perimeter is 28 feet.
Example 5
Solve V  lwh for l.
Solve y  mx  b for x.
Example 6
Solve P  2l  2w for w.
Solve F 
9
C  32 for C.
5
Assignment: Worksheet 2.6
Exit Problem: Create your own word problem using one of these formulas.