© 1999 T
EXAS
I
NSTRUMENTS
I
NCORPORATED
TI-30X
Ù
S: A Guide for Teachers
11
Trig Functions
(Continued)
Activity
Present the following problem to students:
You need to build a ramp to your front door. The
distance from the ground to the bottom of the door
is 1.5 feet. You dont want the angle of incline to be
more than 6 degrees. The distance from the street to
the door is 20 feet. Is there enough room to build the
ramp?
Procedure
1. Make a drawing of the problem.
1.5 ft.
A
20 ft.
2. Use the trigonometric ratio
tan = opposite leg
¾
adjacent leg
to find angle
A
.
Angle A is 4.3 degrees (rounded to the nearest
tenth). Yes, there is enough room to build the
ramp.
³
1. Press
%
\
.
tan
-1
(
2. Enter 1.5
W
20 and press
E
<
.
tan
-1
(1.5/20)
4.3
Extension
Present the following problem to students:
You want to start the ramp 15 feet away from the
door. Can you do that and still have the angle of
incline be less than 6 degrees?
Yes, angle A is 5.7º.
³
1. Press
%
\
.
tan
-1
(
2. Enter 1.5
¾
¾
15 and press
<
.
tan
-1
(1.5/15
5.7
