/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 35 A cargo ship is 4.2 miles from a... [FREE SOLUTION] | 91Ó°ÊÓ

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A cargo ship is 4.2 miles from a lighthouse, and a fishing boat is 5.0 miles from the lighthouse, as shown below. The angle between the straight lines from the lighthouse to the 2 vessels is \(5^{\circ}\) . The approximate distance, in miles, from the cargo ship to the fishing boat is given by which of the following expressions? (Note: The law of cosines states that for any triangle with vertices \(A, B,\) and \(C\) and the sides opposite those \(\left.c^{2}=a^{2}+b^{2}-2 a b \cos C .\right)\) A. \(\sqrt{(5.0)^{2}-(4.2)^{2}}\) B. \(\sqrt{(4.2)^{2}+(5.0)^{2}-2 \cdot 4.2 \cdot 5.0 \cos 5^{\circ}}\) C. \(\sqrt{(4.2)^{2}+(5.0)^{2}+2 \cdot 4.2 \cdot 5.0 \cos 5^{\circ}}\) D. \(\sqrt{(4.2)^{2}+(5.0)^{2}-2 \cdot 4.2 \cdot 5.0 \cos 85^{\circ}}\) E. \(\sqrt{(4.2)^{2}+(5.0)^{2}+2 \cdot 4.2 \cdot 5.0 \cos 85^{\circ}}\)

Short Answer

Expert verified
Answer: The distance is given by \(\sqrt{(4.2)^{2}+(5.0)^{2}-2 \cdot 4.2 \cdot 5.0 \cos 5^{\circ}}\).

Step by step solution

01

Identifying the given information

We know the following information from the problem statement: - The angle between lighthouse and 2 vessels \(A=5^{\circ}\) - The distance from the lighthouse to cargo ship \(b=4.2\) miles - The distance from the lighthouse to fishing boat \(c=5.0\) miles
02

Apply the Law of Cosines

Using the given information and the Law of Cosines, we can find the distance between the cargo ship and fishing boat (a). \(a^{2}=b^{2}+c^{2}-2bc\cos{A}\) Plug in the values: \(a^{2} = (4.2)^{2}+(5.0)^{2}-2(4.2)(5.0)\cos{5^{\circ}}\)
03

Calculate the distance (a)

Solve the equation for the distance (a) by taking the square root of both sides: \(a = \sqrt{(4.2)^{2}+(5.0)^{2}-2(4.2)(5.0)\cos{5^{\circ}}}\) This expression matches the option B in the given choices. So, the correct answer is B. \(\sqrt{(4.2)^{2}+(5.0)^{2}-2 \cdot 4.2 \cdot 5.0 \cos 5^{\circ}}\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Geometry
Geometry, one of the classical disciplines of math, is an essential tool for solving problems involving shapes, sizes, and configurations. In the context of trigonometry and specifically the Law of Cosines, geometry provides the framework for understanding how to relate the sides and angles of a triangle.

In practical terms, when we're dealing with a scenario like calculating the distance between a cargo ship and a fishing boat with a known landmark (the lighthouse), we're forming a triangle. The distances from the lighthouse to each vessel form two sides of this triangle, and the specified angle at the lighthouse becomes one of the triangle's interior angles.

Using geometry, we can understand that the Law of Cosines is a way to translate the relationships in the triangle into a solvable equation, allowing us to calculate the unknown length – the third side of the triangle. It's like putting together the pieces of a puzzle where each side and angle is a clue.
Trigonometry
Trigonometry is the branch of mathematics that deals with the relationships between the sides and angles of triangles. While often associated with right triangles, trigonometry also has functions, such as the Law of Cosines, that apply to oblique (non-right) triangles.

In our exercise, we use the Law of Cosines to find the unknown side opposite the given angle. The formula steps back from the more commonly known right triangle trigonometry, where functions like sine and cosine strictly apply to right angles, and shows that we can calculate the measurements for any triangle. This is vital not only in academic studies but also in real-world applications, such as navigation, surveying, and even in electronics and physics.

Trigonometry is a critical part of the ACT math practice, providing a foundation for problem-solving and analytical thinking skills essential for the ACT test and further STEM education.
ACT Math Practice
Preparing for the ACT Math section involves mastering various mathematical skills, one of which is trigonometry. Questions often feature real-world situations that require the application of concepts such as the Law of Cosines.

To improve your ACT math practice, focus on understanding the principles behind formulas like the one used in this geometry problem, as opposed to just memorizing them. Know how to identify which formula to use based on the information given in the problem, and practice applying these formulas to different scenarios to build confidence.

Additionally, work on honing your skills to decipher word problems accurately and ensure that you're extracting the correct values for your calculations. Keep in mind that questions are specifically designed to test not only your mathematical expertise but also your critical thinking and problem-solving abilities, essential for success in the ACT and future academic pursuits.

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