Chapter 7: Problem 11
Solve the given triangles. $$ \alpha=16.3^{\circ}, \gamma=47.6^{\circ}, c=211 \mathrm{yd} $$
Short Answer
Expert verified
The triangle is solved: \( \beta = 116.1^\circ \), \( a \approx 80.35 \text{ yd} \), \( b \approx 253.03 \text{ yd} \).
Step by step solution
01
Determine Angle Beta
We use the fact that the sum of angles in a triangle is 180 degrees. Therefore, \[ \beta = 180^{\circ} - \alpha - \gamma = 180^{\circ} - 16.3^{\circ} - 47.6^{\circ} = 116.1^{\circ}. \]
02
Use the Law of Sines for Side a
The Law of Sines states that \( \frac{a}{\sin(\alpha)} = \frac{b}{\sin(\beta)} = \frac{c}{\sin(\gamma)} \). We can solve for side \( a \) using:\[ a = c \cdot \frac{\sin(\alpha)}{\sin(\gamma)} = 211 \cdot \frac{\sin(16.3^{\circ})}{\sin(47.6^{\circ})}. \]
03
Calculate Side a
Using a calculator, compute the sines and solve for \( a \):\[ a \approx 211 \cdot \frac{0.2806}{0.7367} \approx 80.35 \text{ yd}. \]
04
Use the Law of Sines for Side b
Now solve for side \( b \) using:\[ b = c \cdot \frac{\sin(\beta)}{\sin(\gamma)} = 211 \cdot \frac{\sin(116.1^{\circ})}{\sin(47.6^{\circ})}. \]
05
Calculate Side b
Using a calculator, compute the necessary values to find \( b \):\[ b \approx 211 \cdot \frac{0.8829}{0.7367} \approx 253.03 \text{ yd}. \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Angle Sum Property
In the world of triangles, the angle sum property is a fundamental concept. It states that the total measure of the interior angles of any triangle is always 180 degrees. Understanding this property is crucial when solving for unknown angles in a triangle. Let's say you know two angles of a triangle; in this case, \( \alpha = 16.3^{\circ} \) and \( \gamma = 47.6^{\circ} \). To find the third angle, \( \beta \), you simply subtract the sum of the known angles from 180 degrees:
- First, add \( \alpha \) and \( \gamma \): \( 16.3^{\circ} + 47.6^{\circ} = 63.9^{\circ} \).
- Next, subtract this sum from \( 180^{\circ} \): \( 180^{\circ} - 63.9^{\circ} = 116.1^{\circ} \).
Law of Sines
The Law of Sines is a key formula used in trigonometry for solving triangles, particularly when dealing with non-right triangles. This law is incredibly helpful, especially when you know one side and two angles. It follows the principle:\[ \frac{a}{\sin(\alpha)} = \frac{b}{\sin(\beta)} = \frac{c}{\sin(\gamma)} \]This relationship tells us that the ratio of any side of a triangle to the sine of its opposite angle is always the same. For example, if you know \( \alpha = 16.3^{\circ} \), \( \gamma = 47.6^{\circ} \), and side \( c = 211 \) yards, you can find side \( a \) by rearranging the formula:
- \( a = c \cdot \frac{\sin(16.3^{\circ})}{\sin(47.6^{\circ})} \)
- Calculate to find \( a \approx 80.35 \) yards.
- \( b = c \cdot \frac{\sin(116.1^{\circ})}{\sin(47.6^{\circ})} \)
- Find \( b \approx 253.03 \) yards.
Sine Function
The sine function is one of the essential trigonometric functions you will encounter when dealing with triangles. It relates the angle of a right triangle to the length of the opposite side and the hypotenuse.In formula terms, for an angle \( \theta \) in a right triangle, the sine function is expressed as: \( \sin(\theta) = \frac{\text{opposite side}}{\text{hypotenuse}} \)This function comes into play in scenarios like the Law of Sines, providing the necessary link between an angle and the triangle's sides. For example:
- The sine of \( 16.3^{\circ} \) is approximately 0.2806.
- The sine of \( 47.6^{\circ} \) is approximately 0.7367.
- The sine of \( 116.1^{\circ} \), derived from the angle sum property, is about 0.8829.