Chapter 1: Problem 28
The length of a rectangle is 3 feet more than its width. If the perimeter is 46 feet, then what is the width?
Short Answer
Expert verified
The width is 10 feet.
Step by step solution
01
- Understand the Problem
The problem states that the length (L) of a rectangle is 3 feet more than its width (W). The perimeter of the rectangle is given as 46 feet. We need to find the width.
02
- Write Down the Formula
The formula for the perimeter (P) of a rectangle is given by \[ P = 2 \times (L + W) \] Given that the perimeter (P) is 46 feet, we substitute P in the formula.
03
- Express Length in Terms of Width
Since the length (L) is 3 feet more than the width (W), we can write \[ L = W + 3 \]
04
- Substitute L in the Perimeter Formula
Substitute \( L = W + 3 \) in the perimeter formula: \[ 46 = 2 \times ((W + 3) + W) \]
05
- Simplify the Equation
Simplify the equation: \[ 46 = 2 \times (2W + 3) \] Then \[ 46 = 4W + 6 \]
06
- Solve for Width
Subtract 6 from both sides of the equation: \[ 40 = 4W \] Divide both sides by 4: \[ W = 10 \]
07
- Verify the Solution
Verify the width by calculating the length and perimeter: \[ L = W + 3 = 10 + 3 = 13 \] Perimeter = 2 \times (L + W) = 2 \times (10 + 13) = 46 feet, which matches the given data.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Perimeter of a Rectangle
In geometry, the perimeter of a rectangle is the total distance around the outside of the rectangle. It can be calculated using the formula: \[ P = 2 \times (L + W) \] Where:
- \( P \) is the perimeter
- \( L \) is the length
- \( W \) is the width
System of Equations
A system of equations consists of two or more equations that have common variables. To solve a system of equations, you need to find the values of the variables that satisfy all equations in the system. In this problem, we have two main equations:
- \[ 46 = 2 \times (L + W) \] (perimeter formula)
- \[ L = W + 3 \] (length is 3 feet more than width)
Basic Algebraic Manipulation
Basic algebraic manipulation involves operations like addition, subtraction, multiplication, and division to rearrange and solve equations. This problem requires several steps of manipulation:
- First, express length \( L \) in terms of width \( W \): \[ L = W + 3 \]
- Next, substitute \( L \) into the perimeter formula: \[ 46 = 2 \times ((W + 3) + W) \]
- Simplify the equation: \[ 46 = 2 \times (2W + 3) \]
- Simplify further and solve for \( W \): \[ 46 = 4W + 6 \rightarrow 40 = 4W \rightarrow W = 10 \]
Substitution Method
The substitution method is a common technique for solving systems of equations. Here's how it works:
- Solve one of the equations for one variable.
- Substitute this expression into the other equation.
- Solve the second equation for the remaining variable.
- Substitute the solution back into the first equation to find the other variable's value.