Texas Instruments TI-30X IIS User Manual page 18

Trig Functions
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 don't 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.
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.
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.
© 1999 T I I
EXAS NSTRUMENTS
(Continued)
20 ft.
NCORPORATED
³ 1. Press % \.
2. Enter 1.5 W 20 and press
A
³ 1. Press % \.
2. Enter 1.5 ¾ 15 and press
TI-30X ÙS: A Guide for Teachers
tan -1 (
E <.
tan (1.5/20)
-1
4.3
tan -1 (
<.
tan (1.5/15
-1
5.7
11