1. Using Right Triangles in the Real World
EQ: How do you use right triangles in the
real world?
M2 Unit 2: Day 5

2. Find the height h of the lamppost to the nearest inch.
EXAMPLE 3
Using tangent
Remember…SOHCAHTOA
Example 1
Find the height h of the lamppost to the nearest inch.
tan 70o =
opp. adj.
Write ratio for tangent of 70o.
tan 70o h. =
40.
Substitute.
Multiply each side by 40.
40 ● tan 70o
= h
109.9 h
Use a calculator to simplify.
ANSWER
The lamppost is about 110 inches tall. 2

3. EXAMPLE 4
Example 2
Find a hypotenuse using an angle of depression
You are skiing on a mountain with an altitude of 1200 meters. The angle of depression is 21o. About how far do you ski down the mountain?
About 3349 feet 3

4. Example 3:
loading
dock
4 ft
ramp
32°

5. Example 4:
You lean a 16 foot ladder against the wall. If the ladder forms a 35° with the ground, how far up the wall does the ladder reach?
16ft
35°

6. Example 5:

7. Example 6
Hints:
What’s the difference in the heights of the 2 buildings?
You must find the measure of the angle adjacent to the angle of depression.
35o
120 x

8. Example 7:

9. Example 8
Use a trigonometric ratio to find a hypotenuse
EXAMPLE 3
You want to string cable to make a dog run from two corners of a building, as shown in the diagram. Write and solve a proportion using a trigonometric ratio to approximate the length of cable you will need.
sin 35o =
opp hyp
x =
11.
sin 35o
sin 35o = 11 x
x ≈
11.
0.5736
x ●sin 35o =
x ≈
19.2
ANSWER
You will need a little more than 19 feet of cable. 9

10. Homework:
Handout