Game Development Reference
In-Depth Information
3. Click the Value menu item. To position the Value field, click to the right of
the plus sign. This is the y-intercept of the equation. To raise the y-intercept
3 units above the x axis, type 3 in the field.
4. Now proceed to the lower-right panel, and click the Chart for Formula 1
button to generate the graph. As Figure 10.27 illustrates, the line that results
intersects the
y
axis above the
x
axis.
In Figure 10.26, you created a line that intercepts the
y
axis 3 units above the
x
axis. To create a line that intercepts the
y
axis 3 units below the
x
axis, use the
following steps:
1. Click the menu item for Value. Then click in the lower equation composition
area to position Value field. Type x in the Value field.
2. Click the Subtract menu item. Then click to the right of the Value field to
position the minus sign.
3. Click the Value menu item. To position the Value field, click after the minus
sign. To set the y-intercept 3 units below the x axis, type 3 in this field.
4. To generate the graph of the line, in the lower-right panel click the Chart for
Formula 2 button. As Figure 10.27 illustrates, the resulting graph crosses the
y
axis below the
x
axis.
Odd Exponents and Translations
When you work with odd-numbered exponents and do not translate them up or
down the
y
axis, the graphs you generate are symmetrical with respect to the origin
of the Cartesian plane. When you change the position of the y-intercept for such
equations, the shape of the graph remains the same, but it is no longer symmetrical
with respect to the origin. Figure 10.28 illustrates the graphs of equations con-
taining cubed variables. Both equations take the form
y ¼ x
3
þ b
. On the right
side, the value of
b
is negative. On the left side, the value of
b
is positive.
To use Visual Formula to create graphs of lines generated by equations that
contain variables with odd-numbered exponents, follow these steps (refer to
Figure 10.29):
1. For the first equation
ðy ¼ x
3
þ bÞ
, click the menu item for Value. Then
click in the upper equation composition area to position the Value field.
Type x in the Value field.
