Download Tangent Ratio, part 1

February 11, 2016
Unit 9 Lesson 1
Tangent Ratio, part 1
New facts often trigger new ideas.
- Alex F. Osborn (fun fact: he popularized group brainstorming as a
creativity problem-solving technique)
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Trigonometry - "Study of triangles"
To work with trigonometry we need a right triangle.
We focus on one of the acute angles in the triangle.
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Terminology
Hypotenuse - side opposite the right angle
Opposite Leg - the leg that does not form the angle
Adjacent Leg - the leg that does form the angle
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Example 1: Label the triangle while focusing on angleB.
0
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90
90
100
80
110
120
70
130
60
140
50
0°
40
150
30
160
20
10
0
170
180
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Example 2:
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What does Example 2 allow us to say about any right triangle
with an angle congruent to angleA?
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Tangent Ratio
- relates the opposite leg of an angle to its adjacent leg
this can be shortened to....
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Using a calculator:
Always check the mode and place calculator in "degrees"
In the calculator:
1. Hit the tan button
2. Type your measure of angleA
from the worksheet and close
the parenthesis
3. Hit enter.
4. Compare the value you found in
Step 4 on the WS
* The number in the calculator is telling you
the ratio of the opposite leg to the adjacent leg
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Example 3: Write the tanR and tan T as ratios.
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Example 4:
In the calculator type tan(90). What happens?
Can we take the tangent of a 90 degree angle?
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