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Ch. 5 - Trigonometric Identities
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161Not the one you use?Change textbook
Chapter 6, Problem 5.42

Each expression simplifies to a constant, a single function, or a power of a function. Use fundamental identities to simplify each expression.
1/ tan² α + cot α tan α

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1
Recognize that \( \tan \alpha = \frac{\sin \alpha}{\cos \alpha} \) and \( \cot \alpha = \frac{\cos \alpha}{\sin \alpha} \).
Rewrite \( \frac{1}{\tan^2 \alpha} \) as \( \cot^2 \alpha \) using the identity \( \cot \alpha = \frac{1}{\tan \alpha} \).
Substitute \( \cot^2 \alpha \) for \( \frac{1}{\tan^2 \alpha} \) in the expression.
Simplify \( \cot \alpha \tan \alpha \) to 1, since \( \cot \alpha = \frac{1}{\tan \alpha} \).
Combine the simplified terms: \( \cot^2 \alpha + 1 \).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Trigonometric Identities

Trigonometric identities are equations that involve trigonometric functions and are true for all values of the variables involved. Fundamental identities, such as the Pythagorean identities, reciprocal identities, and quotient identities, are essential for simplifying trigonometric expressions. Understanding these identities allows students to manipulate and transform expressions effectively.
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Fundamental Trigonometric Identities

Reciprocal Functions

Reciprocal functions in trigonometry refer to the relationships between sine, cosine, tangent, and their reciprocals: cosecant, secant, and cotangent. For example, the tangent function is the reciprocal of cotangent, and this relationship is crucial when simplifying expressions. Recognizing these relationships helps in rewriting expressions in a more manageable form.
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Secant, Cosecant, & Cotangent on the Unit Circle

Simplification Techniques

Simplification techniques in trigonometry involve rewriting complex expressions into simpler forms using identities and algebraic manipulation. This may include factoring, combining like terms, or substituting equivalent expressions. Mastering these techniques is vital for solving trigonometric equations and understanding their behavior in various contexts.
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Example 6