Chapter 1. Section 1
Page 1 of 4
C. Bellomo, revised 18-Sep-07
Section 1.1 – Introduction to Graphing
A First Look at Graphs:
• Graphs provide a way to display, interpret and analyze data
• We can measure temperature in two different systems. The English system uses Fahrenheit and the
Metric system uses Celsius
• Freezing is 0o C or 32o F and boiling is 100o C or 212o F
• We can organize this data in what is called a line graph.
• For now, we arbitrarily put Celsius on the horizontal. We will go over some standards of how this is
set up later, but first let's look at the basic element of the graph, which is the point or ordered pair
• The ordered pair is written as (x, y). The value on the horizontal (Celsius in this case) always goes
first in the ordered pair, followed by the value on the vertical
• NOTE: This is an important concept, because no matter what the labels are (x, y) (apples, oranges)
the first term is always on the horizontal
• So what is the ordered pair labeled as "A" in the graph?
• When we have data for these ordered pairs, we can connect them together. In this case we get a
straight line. This means there is a linear relationship between Celsius and Fahrenheit
Some Standards:
• The vertical and horizontal lines are known as axes. The vertical axis and the horizontal axis
• NOTE: The book refers to them as the x axis and the y axis, but this is a bad idea because what if
you don't have an x and a y, but a g and a t?
• The ordered pair (0,0) is known as the origin
• The negative values for the vertical axis are always to the left of the origin, and the negative values
for the horizontal axis are below the origin
• Why do we refer to this as a two dimensional plane?
Temperature (Celsius v s. Fahrenheit)
-200
-150
-100
-50
0
50
100
150
200
250
-100 -50 0 50 100
Cels ius
Fahrenhei
t
A
