Game Development Reference
In-Depth Information
coordinate pairs of the two lines occur in reversed order. Rather than being
perpendicular to each other, the lines are symmetrical.
At the top of Figure 7.10, there is a table in which the coordinate pairs on the left
are the reverse of those on the right. Above the table you see equations that
represent the inverses of each other. The graph shows the two lines.
When you solve the inverse equations using the set of values, the lines that you
generate mirror each other. The line of symmetry can be identified if you use the
equation
y ¼ x
, as the dashed line in Figure 7.10 reveals.
Exercise Set 7.7
Plot values for the following equations to determine if the lines that result are symmetrical to the
line you get when you plot x¼y.
a. x þ y ¼ 6
b. 3x þ 3y ¼ 5
c. yx ¼ 12
d. xy ¼ 4
e. y ¼jx j
Using Visual Formula
Use Visual Formula to implement a linear equation involving an absolute value.
Toward this end, generate a graph that shifts the vertex of the graph to the left on
the
x
axis 4 units. Here is the equation that accomplishes this task:
y ¼j
4
þ
x
j
To implement the equation, refer to Figure 7.11 and use the following steps:
1. Double click the menu item for absolute values (
k
Abs). Then click in the
equation composition area to position the absolute value bars. Use the
mouse cursor to pull the bars for the absolute value area far enough apart to
accommodate two value fields and a plus sign (see Figure 7.11).
2. Click the Value menu item. Position the field just to the right of the left
absolute value bar. Click in the field and type 4.
3. Click the Add menu item and position the plus sign to the right of the Value
field.
