Texas Instruments TI-30X - IIS Scientific Calculator - Trig Functions

© 1999 T
EXAS
I
NSTRUMENTS
I
NCORPORATED
TI-30X ÙS: 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 ÙS
• 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 C4
¾
5 = 0.80
c. tan C3
¾
4 = 0.75
d. sin A4
¾
5 = 0.80
e. cos A3
¾
5 = 0.60
f. tan A4
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
BC
A