Given the vertices of a triangle at , , and , use the Law of Cosines to find, correct to the nearest degree, the three angles of the triangle.
Table of contents
- 0. Review of College Algebra4h 45m
- 1. Measuring Angles40m
- 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
Problem 27
Textbook Question
In Exercises 25–30, use Heron's formula to find the area of each triangle. Round to the nearest square unit.
a = 14 meters, b = 12 meters, c = 4 meters
Verified step by step guidance1
Identify the side lengths of the triangle: \(a = 14\) meters, \(b = 12\) meters, and \(c = 4\) meters.
Calculate the semi-perimeter \(s\) of the triangle using the formula: \(s = \frac{a + b + c}{2}\).
Substitute the values of \(a\), \(b\), and \(c\) into the semi-perimeter formula to find \(s\).
Apply Heron's formula to find the area \(A\) of the triangle: \(A = \sqrt{s(s - a)(s - b)(s - c)}\).
Substitute the values of \(s\), \(a\), \(b\), and \(c\) into Heron's formula and simplify under the square root to find the area before rounding.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Heron's Formula
Heron's formula calculates the area of a triangle when the lengths of all three sides are known. It uses the semi-perimeter, s = (a + b + c) / 2, and the area is found by √[s(s - a)(s - b)(s - c)]. This method avoids needing the height or angles.
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Semi-perimeter of a Triangle
The semi-perimeter is half the perimeter of a triangle, calculated as s = (a + b + c) / 2. It is a key intermediate value in Heron's formula, simplifying the area calculation by incorporating all three side lengths into one term.
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Rounding and Units in Measurement
After calculating the area, it is important to round the result to the nearest whole number as specified. Additionally, the units of area are the square of the length units (e.g., square meters), reflecting the two-dimensional nature of area.
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