Skip to main content
Ch. 7 - Applications of Trigonometry and Vectors
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161당신이 사용하는 게 아니라요?교과서 변경
8장, 문제 21

Solve each triangle ABC that exists.
A = 42.5°, a = 15.6 ft, b = 8.14 ft

검증된 단계별 안내
1
Identify the given elements of the triangle: angle \(A = 42.5^\circ\), side \(a = 15.6\) ft (opposite angle \(A\)), and side \(b = 8.14\) ft (opposite angle \(B\)). We need to find the remaining parts of the triangle: angle \(B\), angle \(C\), and side \(c\).
Use the Law of Sines to find angle \(B\). The Law of Sines states: \(\frac{a}{\sin A} = \frac{b}{\sin B}\). Rearranged to solve for \(\sin B\), it becomes \(\sin B = \frac{b \cdot \sin A}{a}\).
Calculate \(\sin B\) using the values of \(a\), \(b\), and \(A\). Then, find angle \(B\) by taking the inverse sine (arcsin) of \(\sin B\). Remember that the sine function can have two possible angles in the range \(0^\circ\) to \(180^\circ\), so consider both possible solutions for \(B\) (the ambiguous case).
Once angle \(B\) 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 \(c\): \(\frac{c}{\sin C} = \frac{a}{\sin A}\), which rearranges to \(c = \frac{a \cdot \sin C}{\sin A}\). This completes the solution of the triangle.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
도움이 되었나요?

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 Ambiguity (SSA Case)

When two sides and a non-included angle (SSA) are given, there may be zero, one, or two possible triangles. Understanding this ambiguity helps determine if multiple solutions exist or if the triangle is unique or impossible.
추천 영상:
9:50
Solving SSA Triangles ("Ambiguous" Case)

Sum of Angles in a Triangle

The sum of the interior angles in any triangle is always 180°. After finding one unknown angle using the Law of Sines, this property helps find the remaining angle to complete the triangle.
추천 영상:
4:47
Sum and Difference of Tangent