Chapter 11: Problem 24
Solve triangle. \(B=52^{\circ}, C=29^{\circ}, a=43\) centimeters
Short Answer
Expert verified
A = 99°, b ≈ 34.03 cm, c ≈ 21.08 cm.
Step by step solution
01
Find Angle A Using Sum of Angles in a Triangle
The sum of the angles in any triangle is always \(180^{\circ}\). To find angle \(A\), use the formula: \(A = 180^{\circ} - B - C\). Substitute the given values: \(A = 180^{\circ} - 52^{\circ} - 29^{\circ}\). Calculate \(A = 99^{\circ}\).
02
Calculate Side b Using the Law of Sines
Use the law of sines to find side \(b\): \(\frac{a}{\sin A} = \frac{b}{\sin B}\). Substitute the known values into the equation: \(\frac{43}{\sin 99^{\circ}} = \frac{b}{\sin 52^{\circ}}\). Solve for \(b\) by multiplying both sides by \(\sin 52^{\circ}\): \(b = 43 \cdot \frac{\sin 52^{\circ}}{\sin 99^{\circ}}\). Calculate \(b\approx 34.03\) centimeters.
03
Calculate Side c Using the Law of Sines
Use the law of sines again to find side \(c\): \(\frac{a}{\sin A} = \frac{c}{\sin C}\). Substitute the known values into the equation: \(\frac{43}{\sin 99^{\circ}} = \frac{c}{\sin 29^{\circ}}\). Solve for \(c\) by multiplying both sides by \(\sin 29^{\circ}\): \(c = 43 \cdot \frac{\sin 29^{\circ}}{\sin 99^{\circ}}\). Calculate \(c \approx 21.08\) centimeters.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Sum of Angles in a Triangle
Triangular geometry is based on a simple and crucial rule: the sum of all internal angles in a triangle is always equal to \(180^{\circ}\). This is a fundamental principle that helps us solve for unknowns in triangles.
In the given exercise: you are tasked with finding angle \(A\). This becomes easy by subtracting the known angles \(B\) and \(C\) from \(180^{\circ}\):
In the given exercise: you are tasked with finding angle \(A\). This becomes easy by subtracting the known angles \(B\) and \(C\) from \(180^{\circ}\):
- The formula used is \(A = 180^{\circ} - B - C\).
- Substituting the given values \(B = 52^{\circ}\) and \(C = 29^{\circ}\): \(A = 180^{\circ} - 52^{\circ} - 29^{\circ}\).
- Which results in \(A = 99^{\circ}\).
Law of Sines
The Law of Sines is a powerful tool in trigonometry for solving triangles. It finds unknown sides or angles by relating the ratios of each angle to its opposite side. This law states: \[\frac{a}{\sin A} = \frac{b}{\sin B} = \frac{c}{\sin C}\] In our problem, this law lets us find unknown sides \(b\) and \(c\) from the known side \(a = 43\) and angles.
- To find side \(b\), rearrange the equation: \(b = 43 \cdot \frac{\sin 52^{\circ}}{\sin 99^{\circ}}\)
- Similarly, solve for \(c\): \(c = 43 \cdot \frac{\sin 29^{\circ}}{\sin 99^{\circ}}\)
Angle Calculation
When solving triangles, the calculation of unknown angles applies key geometric principles.
In the task, we already knew angles \(B = 52^{\circ}\) and \(C = 29^{\circ}\), and we needed the third angle \(A\).
In the task, we already knew angles \(B = 52^{\circ}\) and \(C = 29^{\circ}\), and we needed the third angle \(A\).
- The principle used was the sum of angles in triangles: \(A + B + C = 180^{\circ}\)
- By rearranging this, \(A = 180^{\circ} - B - C\), simplifying direct calculation.
Side Calculation
Finding side lengths in triangles is often achieved using the Law of Sines.
In this exercise, after determining angle \(A = 99^{\circ}\), and knowing side \(a = 43\), we found sides \(b\) and \(c\):
In this exercise, after determining angle \(A = 99^{\circ}\), and knowing side \(a = 43\), we found sides \(b\) and \(c\):
- To determine \(b\), we plugged values into the rearranged Law of Sines equation: \(b = 43 \cdot \frac{\sin 52^{\circ}}{\sin 99^{\circ}}\), resulting in \(b \approx 34.03\) cm
- For \(c\), we used: \(c = 43 \cdot \frac{\sin 29^{\circ}}{\sin 99^{\circ}}\), resulting in \(c \approx 21.08\) cm