January 12, 2012
January 12, 2012
4.8 Solving Problems with Trig.
1. From a point 100 ft from the base of a tower is 34o.
How tall is this tower?
January 12, 2012
2. From the top of the 120ft tall building a man observes a car
moving toward the building. If the angle of depression changes
from 25o to 45o during the period of observation, how far
does the car travel?
January 12, 2012
January 12, 2012
A ship leaves port at noon and heads due west at 20 knots
(nautical miles per hour). At 2:00pm, the ship changes
direction to N 54 W. Find the ships direction angle from
port and its distance from port at 3:00pm.
January 12, 2012
A U.S. Coast Guard patrol boat leaves port and averages 35
o
knots (nautical mph) traveling 2 hrs at a bearing of 55 and
then 3 hrs at a bearing of 145o. What is the boat's
direction angle and distance from port?
January 12, 2012
Harmonic Motion:
describes the motion of a point on an object that rotates,
oscillates, or vibrates
spring:
max. positive
displacement
equilibrium
equilibrium
max. negative
displacement
period: time to complete one cycle
amplitude: maximum displacement from equilibrium
January 12, 2012
time
d = a sin wt
amp
dist. from origin
at time t
2
If d = 0 at t = 0, then use sin.
d = a cos wt
January 12, 2012
Find a model.
t=0
Displacement
Amp.
Per.
1.
0
8
2
2.
2
2
10