Sharp EL-9900 - Manual (Page 124)

9
Advanced Keyboard/TRIGONOMETRY USING THE SHARP EL-9900
Copyright © 2002, Sharp Electronics Corporation. Permission is granted to photocopy for educational use only.
To solve a trigonometric equation graphically using the
zoom feature:
1. Turn the calculator on and press Y= CL to access and clear Y1 of an old
expression. Set the calculator to degree mode by pressing 2ndF SET UP
B (DRG) and 1 (Deg). Press 2ndF QUIT to exit the menu.
2. To find the solutions of 3sin 2 x – 4sin x + 1 = 0, press 3 ( sin X/
θ/T/n
) a b 2 – 4 sin X/
θ/T/n + 1 ENTER .
3. Set your viewing window to the principal values for sine by pressing
WINDOW (–) 9 0 ENTER 9 0 ENTER 1 0 ENTER (–) 1
ENTER 1 ENTER 1 ENTER . Press GRAPH to view the graph.
4. To save this original graph and viewing window, press ZOOM G (STO) and
1 (StoWin).
5. Set the zoom factors by pressing ZOOM B (FACTOR) ENTER 5
ENTER 5 ENTER . Press GRAPH to exit the menu.
6. To find the left intercept press TRACE and move the cursor near this
intercept by continuing to press the key.
7. Now, press ZOOM A (ZOOM) and 3 (In) to zoom in on
the left intercept and solution of this equation. Press TRACE and to
trace near and approximate the intercept.
8. Return to the original screen by pressing ZOOM H (RCL) and
1 (RclWin). Trace to find the right intercept.
SOLVING TRIGONOMETRIC EQUATIONS
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