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Ch. 7 - Applications of Trigonometry and Vectors
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161, 9780135440780, 9780136881117, 9780135440827, 9780135924891Non è quello che usi tu?Cambia libro di testo
Capitolo 8, Problema 4

CONCEPT PREVIEW Assume a triangle ABC has standard labeling.


a. Determine whether SAA, ASA, SSA, SAS, or SSS is given.


b. Determine whether the law of sines or the law of cosines should be used to begin solving the triangle.


a, B, and C

Guida verificata passo dopo passo
1
Step 1: Identify the given parts of the triangle. The problem states that sides and angles given are 'a', 'B', and 'C'. Here, 'a' is the side opposite angle 'A', and 'B' and 'C' are two angles of the triangle.
Step 2: Determine the type of information given. Since two angles (B and C) and one side (a) are known, this corresponds to the SSA (Side-Side-Angle) case, because you have one side and two angles, but the side is not between the two known angles.
Step 3: Recall the criteria for each case: SAA (two angles and a non-included side), ASA (two angles and the included side), SSA (two sides and a non-included angle), SAS (two sides and the included angle), and SSS (three sides). Since you have two angles and one side opposite an unknown angle, this is SSA.
Step 4: Decide which law to use. The Law of Sines is typically used when you have an angle-side opposite pair and another angle or side, which fits the SSA case here.
Step 5: Conclude that to begin solving the triangle with given 'a', 'B', and 'C', you should use the Law of Sines, which is given by the formula: \(\frac{a}{\sin\left( A \right)} = \frac{b}{\sin\left( B \right)} = \frac{c}{\sin\left( C \right)}\).

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Triangle Congruence and Similarity Criteria

Triangle congruence criteria such as SAA (or AAS), ASA, SSA, SAS, and SSS describe specific combinations of sides and angles that determine a unique triangle. Understanding these helps identify what information is given and what methods apply for solving the triangle.
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30-60-90 Triangles

Law of Sines

The Law of Sines relates the ratios of sides to the sines of their opposite angles in any triangle. It is especially useful when two angles and one side (AAS or ASA) or two sides and a non-included angle (SSA) are known, allowing for the determination of unknown sides or angles.
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Intro to Law of Sines

Law of Cosines

The Law of Cosines generalizes the Pythagorean theorem for any triangle, relating the lengths of sides to the cosine of an included angle. It is typically used when two sides and the included angle (SAS) or all three sides (SSS) are known, enabling calculation of unknown sides or angles.
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Intro to Law of Cosines