18
G
RAPHING
T
ECHNOLOGY
G
UIDE
: TI-82
Copyright © Houghton Mifflin Company. All rights reserved.
Now use shading to solve the previous inequality,
3
14
2
x
x−≥−. The function whose graph forms the lower
boundary is named first in the SHADE command (see Figure 2.53). To enter this in your TI-82, press these keys:
2nd DRAW 7
X,T,θ
– 4 , 1 – 3
X,T,θ
÷ 2 , 2) ENTER (Figure 2.54). The shading extends left from x = 2, hence the
solution to
3
14
2
x
x
−≥−
is the half-line x ≤ 2, or (–∞, 2].
Figure 2.53: DRAW Shade command Figure 2.54: Graph of
3
14
2
x
x−≥−
More information about the DRAW menu is in the TI-82 manual.
2.4 Trigonometry
2.4.1 Degrees and Radians: The trigonometric functions can be applied to angles measured either in radians or
degrees, but you should take care that the TI-82 is configured for whichever measure you need. Press MODE to see
the current settings. Press ▼ twice and move down to the third line of the mode menu where angle measure is
selected. Then press ◄ or ► to move between the displayed options. When the blinking cursor is on the measure
you want, press ENTER to select it. Then press CLEAR or 2nd QUIT to leave the mode menu.
It’s a good idea to check the angle measure setting before executing a calculation that depends on a particular
measure. You may change a mode setting at any time and not interfere with pending calculations. Try the following
keystrokes to see this in action.
Expression Keystrokes Display
sin 45° MODE ▼▼►ENTER
2nd QUIT SIN 45 ENTER .7071067812
sin π° SIN 2nd π ENTER .0548036651
sin π SIN 2nd π MODE ▼▼
ENTER 2nd QUIT ENTER 0
sin 45 SIN 45 ENTER .8509035245
sin
6
π
SIN ( 2nd π ÷ 6) ENTER .5
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