© 1999 T
EXAS
I
NSTRUMENTS
I
NCORPORATED
TI-30X
Ù
S: 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-30X
Ù
S
• pencil
• student activity
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 = 0.60
b. cos
C
4
¾
5 = 0.80
c. tan
C
3
¾
4 = 0.75
d. sin
A
4
¾
5 = 0.80
e. cos
A
3
¾
5 = 0.60
f. tan
A
4
¾
3 = 1.33
³
To set 2 decimal places:
1. Press
%
‚
.
F0123456789
2. Press 2 to select 2
decimal places.
2. Have students find the value of each ratio using
the TI-30X
Ù
S. Round to the nearest 10
thousandth.
a. sin 71°
0.9455
b. tan 31°
0.6009
c. cos 25°
0.9063
³
To find sin 71°:
1. Press
>
.
sin(
2. Enter 71; press
E
<
.
sin(71)
0.945518576
3. Press
%
‚
4.
sin(71)
0.9455
3. Have students find the measure of each angle
using the TI-30X
Ù
S. 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 find
B when sin B=0.4567:
1. Press
%
Z
.
sin
-1
(
2. Enter .4567; press
E
<
.
sin
-1
(.4567)
27.1744
3. Press
%
‚
0
.
sin
-1
(.4567)
27.
5
4
3
B
C
A
