Download Lesson 6 – The Cosine Ratio – Measure

WA10 – Unit 7 – Trigonometry of Right Triangles
Lesson 6 – The Cosine Ratio - Measure
Date: _______________
Lesson 6: The Cosine Ratio - Measure
Finding the Measure of an Angle Using Cos
1) Determine your values of opposite, adjacent, and hypotenuse
2) Substitute values into ratios
3) Find ratio as a decimal
4) Use
cos 1
to find the measure of the angle.
Example 1: In  DEF, identify the side opposite  D and the side adjacent to  D.
Determine the measure of the angles using Cos.
Example 2: Find the measures of the angle you can using the Cosine Ratio
WA10 – Unit 7 – Trigonometry of Right Triangles
Lesson 6 – The Cosine Ratio - Measure
Date: _______________
Worksheet 6
1. Find the Cosine Ratio and the measure of the angle
A
5
4
C
B
2. Find the Cosine Ratio and the measure of the angle
J
G
4
10
H
2. You are building a ramp that has a length of 15 ft. The ramp travels a horizontal distance of
22 ft. What is the angle of elevation?
3. A triangle has the measures 3, 4, and 5. Sketch a drawing of the triangle. Determine the
measure of each angle using the cosine ratio.
4. Determine the following sine ratio to four decimal places:
a) cos 15˚
b) cos 30 ˚
c) cos 60 ˚
d) cos 80 ˚
5. Find the indicated angle:
a)
b)
x
12.4 cm
8.9 cm
7.9 cm
x
6.2 cm