Trigonometry;
Trigonometric Laws and Identities
Sections:
Section 1: Introduction
Section 2
Section 3
Section 4
Section 5
Section 6
Trigonometric Identities and Equations, Page 14
Examples (continued)
Example 4:
Write cos 3
x
cos2
x
as a sum.
Use the Product-Sum Identity:
Next
Previous
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
© 2007 Aventa Learning. All rights reserved.
![cosα cosβ = 1/2 [cos(α + β) + cos(α - β)]; cos3x cos2x = 1/2 [cos(3x + 2x) + cos(3x - 2x)]; cos3x cos2x = 1/2 (cos5x + cosx); cos3x cos2x = cos(5x)/2 + cos(x)/2](../images/MTH08-68.21158.gif)