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

For each expression in Column I, choose the expression from Column II that completes an identity.
6. sec² x = ____


II
A. sin ^2 x/cos ^2 x
B.1/(sec ^2 x)
C. sin (-x)
D. csc ^2 x-cot ^2 x + sin ^2 x
E. tan x

검증된 단계별 안내
1
Recall the Pythagorean identity involving secant and tangent: \(\sec^2 x = 1 + \tan^2 x\).
Understand that this identity comes from dividing the fundamental identity \(\sin^2 x + \cos^2 x = 1\) by \(\cos^2 x\).
Rewrite the expression \(\sec^2 x\) in terms of tangent using the identity: \(\sec^2 x = 1 + \tan^2 x\).
Compare the given expression \(\sec^2 x\) with the options in Column II to find the one that matches \(1 + \tan^2 x\).
Select the expression from Column II that completes the identity as \(1 + \tan^2 x\).

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주요 개념

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

Pythagorean Identity

The Pythagorean identities relate the squares of sine, cosine, and secant functions. One key identity is 1 + tan²x = sec²x, which expresses sec²x in terms of tan²x. This identity is fundamental for transforming and simplifying trigonometric expressions.
추천 영상:
6:25
Pythagorean Identities

Definition of Secant Function

Secant (sec x) is the reciprocal of cosine, defined as sec x = 1/cos x. Understanding this reciprocal relationship helps in manipulating expressions involving sec²x and connecting them to other trigonometric functions like cosine and tangent.
추천 영상:
6:22
Graphs of Secant and Cosecant Functions

Trigonometric Function Squares

Squaring trigonometric functions, such as sec²x or tan²x, is common in identities and equations. Recognizing how these squares relate through identities allows for simplification and solving of trigonometric problems effectively.
추천 영상:
6:04
Introduction to Trigonometric Functions