College Pre-Calc
Trig Identities
Section 6.2: Verifying Trigonometric Identities
Day 1
Two methods for proving identities:
1) Start with the left or right side and
deduce (prove) the other.
2) Work on both sides at the same time to
get two statements that are equal to each other.
College Textbook - "Chapter 6"
1
College Pre-Calc
Section 6.2: Verifying Trigonometric Identities
Day 1
Hints for proving identities:
1) Work with the more complex side first
2) Do simple algebraic manipulations
(what you do to one side...do to the other)
3) Multiply by "1"
4) Convert expressions into sine or cosine
5) Try something
College Textbook - "Chapter 6"
2
College Pre-Calc
Section 6.2: Verifying Trigonometric Identities
Day 1
Example:
Prove the following identity.
sin x
1 + cos x
College Textbook - "Chapter 6"
=
1 - cos x
sin x
3
College Pre-Calc
Section 6.2: Verifying Trigonometric Identities
Day 1
Example:
Prove the following identity.
1 + sec x • sin x • tan x = sec2x
College Textbook - "Chapter 6"
4
College Pre-Calc
Section 6.2: Verifying Trigonometric Identities
Day 1
Example:
Prove the following identity.
1 + sec x • sin x • tan x = sec2x
College Textbook - "Chapter 6"
5
College Pre-Calc
College Textbook - "Chapter 6"
6