To verify the identity sin
2
θ
+ cos
2
θ
= 1, you will graph the "sin
2
θ
+ cos
2
θ
" as
Y1 = sin
2
x
+ cos
2
x
and the "1" as Y2 = 1, and show that they are the same
graph. To do this press Y= to access the Y1 prompt. Press CL to clear Y1 of
an old expression, and enter the sin
2
x
+ cos
2
x
for Y1 by pressing ( sin
X/
θ
/T/
n
) a
b
2 + ( cos X/
θ
/T/
n
) a
b
2 ENTER . Enter the
1 for Y2 by pressing CL 1 ENTER . Press GRAPH to view the graph.
Method of Teaching
Use
Blackline Master 3.1
to create an overhead or handout for graphically
verifying trigonometric formulas and identities. Demonstrate the process
of entering the equality's left- and right-hand expressions and when
necessary, emphasize the intervals where functions are positive or negative
(as demonstrated in
Using Blackline Master 3.2
). Next, use the
Blackline Masters
3.3
through
3.5
to create worksheets for the students. Have the students verify
the various formulas and identities. Use the topics
For Discussion
to supplement
the worksheets.
Graphical Verification of Formulas and Identities/TRIGONOMETRY USING THE SHARP EL-9600
11
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