/*! 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 67 Geometry What are the dimensions... [FREE SOLUTION] | 91Ó°ÊÓ

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Geometry What are the dimensions of a rectangular tract of land when its perimeter is 44 kilometers and its area is 120 square killometers?

Short Answer

Expert verified
The dimensions of the rectangle are either 10 kilometers by 12 kilometers or 12 kilometers by 10 kilometers.

Step by step solution

01

- Setting up the equations

Let the length of the rectangle be \(l\) and the width be \(w\). As per the given problem, we have two direct relationships to use:\n\n - The Perimeter \(P\) of a rectangle is given by \(P = 2(l + w)\). Given \(P = 44\), we can form the equation \(2(l + w) = 44\), which simplifies to \(l + w = 22\).\n\n - The Area \(A\) of a rectangle is given by \(A = lw\). Given \(A = 120\), we can form the equation \(lw = 120\).
02

- Beginning to solve the system of equations

We are now going to solve for one variable in either equation 1 or 2. To keep things easy, we will solve for \(l\) in equation \(l + w = 22\). Therefore, \(l = 22 - w\). Now we have \(l\) in terms of \(w\).
03

- Substituting into the second equation

Now that we have \(l\) in terms of \(w\) we substitute this into our second equation \(lw = 120\), replacing \(l\), we obtain the equation \((22 - w)w = 120\). This is a quadratic equation in the form of \(aw^2 + bw + c = 0\). We can simplify it by expanding and rearranging in standard form: \(w^2 - 22w + 120 = 0\).
04

- Solving the Quadratic Equation

We can solve this quadratic using the quadratic formula \(w = [-(-22) \pm \sqrt{(-22)^2 - 4*1*120}]/2*1\). So the solutions are \(w = 10\) or \(w = 12\). Given that \(w\) represents the width of a rectangle, it cannot logically be two different lengths at the same time, Therefore we have two possible sets of solutions: either \(w = 10\) and \(l = 22 - w = 12\) or \(w = 12\) and \(l = 22 - w = 10\). In other words, it does not matter which one is the width and which one is the length, as both solutions make sense in the context of the problem.

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Key Concepts

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

Solving Quadratic Equations
Understanding how to solve quadratic equations is vital when dealing with numerous types of mathematical problems, such as those found in geometry. The textbook exercise explores a real-world scenario involving the dimensions of land, which leads to a quadratic equation. To solve for a missing dimension, it’s important to note that quadratic equations take the general form of \( ax^2 + bx + c = 0 \). Solutions can be found using various methods, such as factoring, completing the square, or applying the quadratic formula, \( x = [-b \pm \sqrt{b^2 - 4ac}]/2a \).

In the given problem, we used the quadratic formula to find the width (\(w\)) of the rectangular tract of land. After setting up and simplifying the equation to standard form, we applied the formula, carefully handling the plus-minus sign which indicates two possible solutions. These solutions are verified within the context of the problem, confirming their relevance to the rectangular dimensions we seek.
Systems of Equations in Geometry
Systems of equations frequently appear in geometry problems, especially when you're tasked with finding dimensions or coordinates that satisfy multiple conditions. In our textbook problem, the conditions were the perimeter and area of a rectangle. Starting with the known formulas for perimeter and area, we turned the given values into a pair of equations that describe the rectangle: one linear and another quadratic.

Systems can be solved using substitution or elimination methods. Here, we chose substitution. We isolated one variable from the linear equation and substituted that expression into the quadratic equation, a step that eventually led us to the quadratic equation we solved. This strategy is useful for problems where two or more geometric properties are linked, leading to a set of equations that contain the crucial information about the shapes in question.
Rectangular Geometry Applications
Rectangular geometry frequently arises in real-world applications. Knowing how to apply the formulas for the perimeter \( P = 2(l + w) \) and area \( A = lw \) of a rectangle allows us to solve practical problems, like determining the amount of fencing needed for a plot of land or the flooring required for a room.

The textbook exercise shows one such application. After setting up equations based on perimeter and area, we dive into finding the length and width that satisfy both, demonstrating how rectangular geometry is a tool that can be applied to various scenarios. Being able to transition from abstract formulas to specific values based on given information is a key skill in leveraging geometric concepts for practical problem-solving.
Algebraic Problem Solving
Algebraic problem solving involves using algebraic techniques to tackle a wide range of problems. It encourages students to formulate and rearrange equations to make unknown quantities more accessible. Problems like the one in our textbook utilize algebraic manipulation to connect geometric properties with algebraic expressions.

Throughout the exercise, we performed algebraic operations such as substitution and solving quadratic equations to draw closer to our final solution. Additionally, we applied logical reasoning when we concluded that the rectangle could have two sets of dimensions based on the symmetric nature of the problem. This blend of algebra with logic exemplifies algebraic problem solving, a critical skill not only in mathematics but in many problem-solving scenarios encountered in various fields.

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Most popular questions from this chapter

In Exercises 73 and 74, determine whether the statement is true or false. Justify your answer. The area of the figure defined by the system $$\left\\{\begin{array}{l}{x \geq-3} \\ {x \leq 6} \\ {y \leq 5} \\ {y \geq-6}\end{array}\right.$$ is 99 square units.

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If a linear programming problem has a solution, then it must occur at a _____ of the set of feasible solutions.

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