# 2 of 2-Trig

1. Aug 18, 2005

### TonyC

2 of 2--Trig

Kahleela starts the engine on her small airplane. The engine drives a prop with a radius of 8.5 feet and its centerline 11.5 feet above the ground. At idel, the prop rotates at a constant speed of @ 800 revs/minute. The height of one prop tip as a function of time is given by:
h=11.5+8.5sin(800t), where h is the height in feet and t is the time in minutes. When t= 12 minutes, what is h?

I came up with 7.3 feet......I was wrong....

Where did I stray? :yuck:

2. Aug 18, 2005

### hhh79bigo

Last edited: Aug 18, 2005
3. Aug 18, 2005

### TonyC

a. 4.1 ft
b. 18.9 ft
c. 7.3 ft
d. 15.7 ft

4. Aug 18, 2005

### HallsofIvy

Staff Emeritus
12*800= 9600. Assuming that is in degrees, which seems most likely, sin(9600)= -0.8660. 8.5sin(9600)= -7.36 (is that where you got the "7.3"? Did you forget the last part?) 11.5+ 8.5sin(9600)= 4.14. The tip of the propellor is 4.14 feet off the ground.