For Mr. Blair's Pre-Calculus Class. By: Morgen and Elsa 1/13/11

1. Pre-Calculus
5º Pre Calculus
Mr. Blair
Morgen and Elsa

2. Problem #5
• The base of a television antenna and two
points on the ground are in a straight line.
The two points are 100 ft. apart. From the
two points, the measurements of the angles
of elevation to the top are 30º and 20º
respectively. Find the height of the antenna
to the nearest foot.

3. Diagram
h for antenna
20º 30º
|--------100ft--------| |----------x---------|

4. Calculations
• tan30 = h
1 x h = tan30(x) ✴multiply
Cross
• tan20 = h h= tan20(100 + x) and solve
1 100 + x for both h’s
• Set “h’s” equal to each other: .5773x = 36.37 + .3639x
• solve for x. X = 170.6
• put back into first equation to solve for “h”
• tan30 = h
1 170.6
• Solve for h
• Height = 98.5 feet.

5. Problem #18
• A student looks out of a second story
school window and sees the top of the
school flag pole at an angle of elevation of
22º. The student is 18 feet above the
ground and 50 feet from the flag pole. Find
the height of the flag pole.

6. Diagram
School Building
22º
18 ft. Flag Pole
50 ft

7. Calculations
|
22º x
|
|
tan22 x |
1. Find X 1 = 50 18’
|
|
|-------50’--------|
2. X = 20.2
3. Add 20.2 to 20.2
original student’s +18.0
✴Flagpole’s height
= 38.2 ft.
height from 38.2
ground.

8. Any