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Ch. 7 - Applications of Trigonometry and Vectors
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161당신이 사용하는 게 아니라요?교과서 변경
8장, 문제 7.19

Find the unknown angles in triangle ABC for each triangle that exists.


A = 142.13°, b = 5.432 ft, a = 7.297 ft

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1
Step 1: Use the Law of Sines to find angle B. The Law of Sines states that \( \frac{a}{\sin A} = \frac{b}{\sin B} \). Substitute the known values: \( \frac{7.297}{\sin 142.13^\circ} = \frac{5.432}{\sin B} \).
Step 2: Solve for \( \sin B \) by rearranging the equation: \( \sin B = \frac{5.432 \cdot \sin 142.13^\circ}{7.297} \).
Step 3: Calculate \( \sin B \) using the value obtained from Step 2.
Step 4: Determine angle B by taking the inverse sine (arcsin) of \( \sin B \).
Step 5: Find angle C using the fact that the sum of angles in a triangle is 180°. Use the equation: \( C = 180^\circ - A - B \).

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주요 개념

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

Triangle Sum Theorem

The Triangle Sum Theorem states that the sum of the interior angles of a triangle is always 180 degrees. This fundamental principle allows us to find unknown angles when at least one angle is known. In this case, knowing angle A enables us to calculate the other two angles by subtracting A from 180°.
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Solving Right Triangles with the Pythagorean Theorem

Law of Sines

The Law of Sines relates the lengths of the sides of a triangle to the sines of its angles. It is expressed as a/b = sin(A)/sin(B) = c/sin(C). This law is particularly useful in non-right triangles, allowing us to find unknown angles or sides when we have sufficient information, such as two sides and a non-included angle.
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Intro to Law of Sines

Angle of Elevation and Depression

The angle of elevation is the angle formed by the line of sight when looking up from a horizontal line, while the angle of depression is formed when looking down. Understanding these angles is crucial in trigonometry, especially in real-world applications involving heights and distances, as they often require the use of trigonometric ratios to solve for unknown values.
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Coterminal Angles