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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 29

Solve each triangle ABC that exists.


B = 39.68°, a = 29.81 m, b = 23.76 m

검증된 단계별 안내
1
Identify the given elements of the triangle: angle \(B = 39.68^\circ\), side \(a = 29.81\) m (opposite angle \(A\)), and side \(b = 23.76\) m (opposite angle \(B\)). We need to find the remaining parts of the triangle: angle \(A\), angle \(C\), and side \(c\).
Use the Law of Sines to find angle \(A\). The Law of Sines states: \(\frac{a}{\sin A} = \frac{b}{\sin B}\). Rearranged to solve for \(\sin A\), it becomes \(\sin A = \frac{a \sin B}{b}\).
Calculate \(\sin A\) using the values of \(a\), \(b\), and \(B\). Then find angle \(A\) by taking the inverse sine (arcsin) of \(\sin A\). Remember to consider the possible ambiguous case in the Law of Sines where two different angles could satisfy the sine value.
Once angle \(A\) is found, calculate angle \(C\) using the fact that the sum of angles in a triangle is \(180^\circ\): \(C = 180^\circ - A - B\).
Finally, use the Law of Sines again to find side \(c\) by applying \(\frac{c}{\sin C} = \frac{a}{\sin A}\), and solve for \(c\).

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주요 개념

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

Law of Sines

The Law of Sines relates the sides and angles of a triangle through the ratio a/sin(A) = b/sin(B) = c/sin(C). It is essential for solving triangles when two sides and an angle are known, allowing calculation of unknown angles or sides.
추천 영상:
4:27
Intro to Law of Sines

Triangle Angle Sum Property

The sum of the interior angles in any triangle is always 180°. Knowing one or two angles allows determination of the remaining angle, which is crucial for completing the triangle solution.
추천 영상:
4:47
Sum and Difference of Tangent

Ambiguous Case of the Law of Sines (SSA Condition)

When two sides and a non-included angle are given (SSA), there may be zero, one, or two possible triangles. Understanding this ambiguity helps determine all valid solutions or recognize when no triangle exists.
추천 영상:
9:50
Solving SSA Triangles ("Ambiguous" Case)