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Ch. 5 - Trigonometric Identities
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161당신이 사용하는 게 아니라요?교과서 변경
6장, 문제 5.30

Factor each trigonometric expression.
cot⁴ x + 3 cot² x + 2

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1
Recognize that the expression \( \cot^4 x + 3 \cot^2 x + 2 \) can be treated as a quadratic in terms of \( \cot^2 x \).
Let \( u = \cot^2 x \). Then the expression becomes \( u^2 + 3u + 2 \).
Factor the quadratic expression \( u^2 + 3u + 2 \) by finding two numbers that multiply to 2 and add to 3.
The numbers 1 and 2 satisfy these conditions, so the expression factors as \( (u + 1)(u + 2) \).
Substitute back \( u = \cot^2 x \) to get the factored form \( (\cot^2 x + 1)(\cot^2 x + 2) \).

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Trigonometric Identities

Trigonometric identities are equations involving trigonometric functions that are true for all values of the variable. Understanding these identities, such as the Pythagorean identities, can help simplify and manipulate trigonometric expressions. In this case, recognizing that cotangent can be expressed in terms of sine and cosine may aid in factoring the expression.
추천 영상:
5:32
Fundamental Trigonometric Identities

Factoring Polynomials

Factoring polynomials involves rewriting a polynomial as a product of its factors. This process is essential for simplifying expressions and solving equations. In the given expression, recognizing it as a quadratic in terms of cot² x allows us to apply factoring techniques similar to those used in algebra.
추천 영상:
6:08
Factoring

Quadratic Form

A quadratic form is an expression that can be written in the standard form ax² + bx + c. In the context of the given expression, cot⁴ x + 3 cot² x + 2 can be treated as a quadratic in cot² x. This perspective enables the use of factoring methods to find the roots or simplify the expression effectively.
추천 영상:
6:36
Quadratic Formula