Table of contents
- 0. Review of College Algebra4h 43m
- 1. Measuring Angles39m
- 2. Trigonometric Functions on Right Triangles2h 5m
- 3. Unit Circle1h 19m
- 4. Graphing Trigonometric Functions1h 19m
- 5. Inverse Trigonometric Functions and Basic Trigonometric Equations1h 41m
- 6. Trigonometric Identities and More Equations2h 34m
- 7. Non-Right Triangles1h 38m
- 8. Vectors2h 25m
- 9. Polar Equations2h 5m
- 10. Parametric Equations1h 6m
- 11. Graphing Complex Numbers1h 7m
7. Non-Right Triangles
Law of Cosines
9:14 minutes
Problem 3b
Textbook Question
Textbook QuestionIn Exercises 1–12, solve each triangle. Round lengths to the nearest tenth and angle measures to the nearest degree. If no triangle exists, state 'no triangle.' If two triangles exist, solve each triangle. B = 66°, a = 17, c = 12
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Law of Sines
The Law of Sines is a fundamental principle in trigonometry that relates the ratios of the lengths of sides of a triangle to the sines of its angles. It states that for any triangle, the ratio of a side length to the sine of its opposite angle is constant. This law is particularly useful for solving triangles when given two angles and one side (AAS or ASA) or two sides and a non-included angle (SSA).
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Triangle Existence Criteria
To determine if a triangle can exist with given side lengths and angles, one must consider the triangle inequality theorem and the conditions for angle-side relationships. Specifically, the sum of the angles in a triangle must equal 180 degrees, and the lengths of any two sides must be greater than the length of the third side. If these conditions are not met, it may be concluded that 'no triangle' exists.
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30-60-90 Triangles
Ambiguous Case of SSA
The ambiguous case occurs when two sides and a non-included angle (SSA) are known, leading to the possibility of zero, one, or two triangles. This situation arises because the given angle may correspond to two different configurations of the triangle. To resolve this, one must analyze the given information and apply the Law of Sines to check for multiple solutions or the absence of a triangle.
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