Texas Instruments TI-34 II Explorer Plus - Trig Functions

© 1999 T
EXAS
I
NSTRUMENTS
I
NCORPORATED
TI-34 Û: A Guide for Teachers
10
Trig Functions
Overview
Students practice solving sine, cosine, and tangent
ratios, and solve problems involving trigonometric
ratios.
Math Concepts
• multiplication
• division
• trigonometric
ratios
Materials
• TI-34 Û
• pencil
• student activity
(page 12)
Introduction
Introduce the trigonometric ratios to students.
sin = opposite leg
¾
hypotenuse
cos = adjacent leg
¾
hypotenuse
tan = opposite leg
¾
adjacent leg
1. Have students find the trigonometric ratios for
the triangle using the above definitions. Round to
the nearest hundredth if necessary. (Use % ‚
for rounding.)
a. sin C 3
¾
5 = 0.6
b. cos C4
¾
5 = 0.8
c. tan C3
¾
4 = 0.75
d. sin A4
¾
5 = 0.8
e. cos A3
¾
5 = 0.6
f. tan A4
¾
3 = 1.33
2. Have students find the value of each ratio using
the TI-34
Ö
. Round to the nearest 10 thousandth.
a. sin 71° 0.9455
b. tan 31° 0.6009
c. cos 25° 0.9063
3. Have students find the measure of each angle
using the TI-34
Ö
. Round to the nearest degree.
a. sin B = 0.4567 27 degrees
b. cos A = 0.6758 47 degrees
c. tan C = 5.83 80 degrees
³ To set 2 decimal places:
1. Press
% ‚
.
F0123456789
2. Press
2
to select 2
decimal places and press
<
.
³ To find sin 65°,
1. Press % ‚
4
.
2. Press % B <.
sin(
3. Enter
65
, and press
E
<
.
sin(65)
0.9063
³ To find
A when sin A = 0.2756:
1. Press
% ‚
0
.
2. Press
%
B " <.
sin
-1
(
3. Enter
0.2756
, and press
E <
.
sin
-1
(0.2756
¹¹
16
5
4
3
BC
A