Download Tangent Ratio, part 1

February 06, 2017
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)
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
Example 1: Label the triangle while focusing on angleB.
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1. Go to my website (www.tinyurl.com/WrightGeometry)
2. Scroll down to Unit 8, Lesson 1 and select the Tangent Ratio Link.
3. Select the 3rd check box
4. Answer the following questions.
Q1: What side lengths are being highlighted in relation to the angle?
Q2: Select an angle with the blue slider and then change the size of the triangle
using the dots. What do you notice about the ratio being calculated?
Q3: Select a different angle with the blue slider and then change the size of the
triangle using the dots. What do you notice about the ratio being calculated?
Q4: If the measure of the angle is changed, what happens to the value of the ratio?
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Example 2:
What does Example 2 allow us to say about any right triangle
with an angle congruent to angle A?
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Tangent Ratio
- relates the opposite leg of an angle to its adjacent leg
this can be shortened to....
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 angle that you last used in GeoGebra
3. Hit enter.
4. Compare the value to what you see on GeoGebra.
* 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.
Example 4:
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Example 5:
Example 6:
In the calculator type tan(90). What happens?
Can we take the tangent of a 90 degree angle?
February 06, 2017