Chapter 9: Problem 5
Solve the triangles with the given parts. $$c=4380, A=37.4^{\circ}, B=34.6^{\circ}$$
Short Answer
Expert verified
The sides are \( a \approx 2812.35 \) and \( b \approx 2652.34 \); angle C is 108°.
Step by step solution
01
Determine Angle C
To find angle C in the triangle, use the fact that the sum of the angles in any triangle is 180°. Therefore, angle C can be calculated as follows: \[ C = 180° - A - B = 180° - 37.4° - 34.6°. \] Thus, \[ C = 108°. \]
02
Use the Law of Sines to Find Side a
The Law of Sines states \( \frac{a}{\sin A} = \frac{b}{\sin B} = \frac{c}{\sin C} \). We'll use this to find side \( a \):\[ \frac{a}{\sin 37.4°} = \frac{4380}{\sin 108°}. \]Solving for \( a \), we get \[ a = 4380 \times \frac{\sin 37.4°}{\sin 108°}. \]After calculating, \( a \approx 2812.35 \) units.
03
Use the Law of Sines to Find Side b
Apply the Law of Sines again to solve for side \( b \):\[ \frac{b}{\sin 34.6°} = \frac{4380}{\sin 108°}. \]Therefore, \( b = 4380 \times \frac{\sin 34.6°}{\sin 108°}. \)After performing the calculations, \( b \approx 2652.34 \) units.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Law of Sines
The Law of Sines is a powerful tool in trigonometry, especially for solving triangles when given either two angles and a side (AAS or ASA) or two sides and a non-included angle (SSA). This law states:\[ \frac{a}{\sin A} = \frac{b}{\sin B} = \frac{c}{\sin C} \]This means that in any triangle, the ratio of the length of a side to the sine of its opposite angle is constant.
- To use this law effectively, you should know at least one pair of a side and its opposite angle.
- In our example, we start with side \( c = 4380 \) and angle \( C = 108^\circ \). We used the other known angles, \( A = 37.4^\circ \) and \( B = 34.6^\circ \), to solve for sides \( a \) and \( b \).
- The Law of Sines helps us convert angle information into length information based on these angle-side pair relationships by rearranging the formula to solve for unknown sides.
Angle Sum Property
The Angle Sum Property is a foundational concept in triangle geometry. It tells us that the sum of the interior angles in a triangle is always 180 degrees.
- To apply this in triangle solving: If you are given two angles, you can easily find the third by subtracting the sum of the given angles from 180°.
- In this exercise, we have \( A = 37.4^\circ \) and \( B = 34.6^\circ \). By inserting these values into the formula: \[ C = 180^\circ - A - B \]We get:\[ C = 180^\circ - 37.4^\circ - 34.6^\circ = 108^\circ \]
- This property is not just useful in calculations but also serves as a checkpoint to ensure that your solved angles add correctly.
Triangle Solving
Triangle solving involves finding unknown parts of a triangle when given some initial information. Often, we are tasked with finding missing sides and angles using a mix of geometric laws and properties.
- Start with what you know. Identify given sides and angles. This helps determine which mathematical principles you can use.
- Using the Angle Sum Property, determine any unknown angle. As in our case, with two angles known, it was straightforward to find angle \( C \).
- Apply the Law of Sines or Cosines as needed. Since we had angle-side pairs, the Law of Sines was ideal for finding the unknown sides \( a \) and \( b \).
- Perform all calculations carefully, most importantly, solve step-by-step to avoid errors.
- Finally, verify your answers. Ensure that the triangle's internal angle sum is 180° and the solved proportions align with the Law of Sines.