1. Indirect Measurement and Trigonometry
Algebra 2
Mr. Seavy

2. Example 1 How would you find the value of x?
You can use the Pythagorean Theorem because it is a right triangle with two sides given.

3. Example 2 How would you find the value of S?
First you must know that the triangles are similar.

4. Similarity Two polygons are similar if…..
their corresponding angles are congruent
Congruent: equal measurement
AND
their corresponding sides are proportional
Proportional: having equal ratios or scale
Ex: 3 times bigger, shrunk by ¼, 5.23 times bigger
Similar figures are commonly seen in shadow problems or when a dilation is performed.

5. Similarity Example
Find a and b.

6. Example 3 How would you find the values of a and c in this triangle?
We need a new method because we do not have two sides.

7. Trigonometry Ratios

8. Identify Trig Ratios

9. Example Draw the following situation:
A 12 ft ladder is leaning up against a wall. The angle between the ladder and the ground is 58o. How high up the wall will the ladder go?

10. Applying Trig Ratios

11. Additional Practice
Find x and y.

12. Finding an angle given the sides
Use the inverse trig functions found in the calculator to figure out the measure of an angle given the measurements of the sides.
sin-1, cos-1, tan-1

13. Examples
Find the measure of the indicated angle using the ratio of your choice.