Sharp EL-9600, Руководство пользователя

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62 Blackline Masters/TRIGONOMETRY USING THE SHARP EL-9600
Cop
yr
ight ©
1998, Shar
p Electronics Cor
por
ation.
P
e
rmission is g
ranted to photocop
y f
or educational use only
.
Verify the half angle formula cos ( ) = ± ( ) :
1. To verify the formula, you will graph Y1 = cos and Y2 = ± ( )
and show that they are in fact th same graph.
2. In this problem you will need to limit your domain or x values to intervals
where cosine is either negative or positive and enter the appropriate radical
for Y2.
3. To do this you will turn the calculator on and press Y= . Press CL to clear
Y1 of an old expression.
4. Now, enter the cos for Y1 by pressing cos X/
θ
/T/ n a/b 2 ENTER
and the ( ) for Y2 (limiting to where cosine is positive) by
pressing CL 2ndF a/b 1 + cos X/
θ
/T/ n
▼
2 ENTER .
5. Cos ( ) will be positive for a viewing window of 0 < x <
π
. Enter this
viewing window by pressing WINDOW 0 ENTER 2ndF
π
ENTER
2ndF
π
÷ 2 ENTER (–) 3 ENTER 3 ENTER 1 ENTER .
6. Press GRAPH to view the graphs. Notice they appear as one graph.
7. To verify the formula for where cosine is negative, press Y=
▼
to access
the Y2 prompt and press (–) to insert a negative in front of the radical.
Cos ( ) will be negative for a viewing window of
π
< x < 3
π
. Enter this
viewing window by pressing WINDOW 2ndF
π
ENTER 3 2ndF
π
ENTER . Press GRAPH to view the graphs.
GRAPHICAL VERIFICATION OF FORMULAS AND IDENTITIES
3.2
NAME _____________________________________________________ CLASS __________ DATE __________
θ
2
(1 + cos
θ
)
2
(1 + cos x )
2
x
2
(1 + cos x )
2
x
2
x
2
x
2
√
√
√
√