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Ch. 5 - Trigonometric Identities
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161당신이 사용하는 게 아니라요?교과서 변경
6장, 문제 32

Find the exact value of each expression. See Example 1.
[tan 5π/12 + tan π/4]/[1 - tan 5π/12 tan π/4]

검증된 단계별 안내
1
Recognize that the given expression has the form of the tangent addition formula: \(\frac{\tan A + \tan B}{1 - \tan A \tan B} = \tan(A + B)\). Here, identify \(A = \frac{5\pi}{12}\) and \(B = \frac{\pi}{4}\).
Calculate the sum of the angles inside the tangent function: \(A + B = \frac{5\pi}{12} + \frac{\pi}{4}\). To add these, find a common denominator for the fractions.
Convert \(\frac{\pi}{4}\) to twelfths: \(\frac{\pi}{4} = \frac{3\pi}{12}\). Now add the angles: \(\frac{5\pi}{12} + \frac{3\pi}{12} = \frac{8\pi}{12}\).
Simplify the fraction \(\frac{8\pi}{12}\) to \(\frac{2\pi}{3}\). So, the expression simplifies to \(\tan\left(\frac{2\pi}{3}\right)\).
Recall or determine the exact value of \(\tan\left(\frac{2\pi}{3}\right)\) using the unit circle or reference angles to find the final exact value.

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주요 개념

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

Tangent Addition Formula

The tangent addition formula states that tan(A + B) = (tan A + tan B) / (1 - tan A * tan B). This identity allows us to combine or break down tangent expressions involving sums of angles, which is essential for simplifying the given expression.
추천 영상:
3:17
Inverse Tangent

Exact Values of Special Angles

Certain angles like π/4 (45°) have well-known exact trigonometric values, such as tan(π/4) = 1. Recognizing these values helps in simplifying expressions without approximations, ensuring the answer is exact.
추천 영상:
04:39
45-45-90 Triangles

Angle Conversion and Decomposition

Angles like 5π/12 can be expressed as sums of special angles (e.g., π/3 + π/4). Decomposing complex angles into sums of known angles enables the use of addition formulas and exact values to find precise trigonometric values.
추천 영상:
04:46
Coterminal Angles