Math Problem Statement

Ezra is finding the perimeter of different-sized regular pentagons. He finds the perimeter is always 5 times longer than the side length.

There is a proportional relationship between the side length of the regular pentagon in 

inches,   x

,

 and the perimeter of the regular pentagon in 

inches,   y

.

Graph this relationship. Select two points to draw a line.

Solution

Ezra observed that the perimeter of a regular pentagon is always 5 times the side length. This means that the relationship between the side length xx and the perimeter yy can be expressed as:

y=5xy = 5x

This equation shows a direct proportionality between the side length and the perimeter of the pentagon.

Step 1: Identify two points.

To graph this relationship, we can choose two points that satisfy the equation.

  1. When the side length x=1x = 1: y=5×1=5y = 5 \times 1 = 5 So, one point is (1,5)(1, 5).

  2. When the side length x=2x = 2: y=5×2=10y = 5 \times 2 = 10 So, another point is (2,10)(2, 10).

Step 2: Plot the points and draw the line.

To graph the relationship:

  • Plot the point (1,5)(1, 5) on the graph.
  • Plot the point (2,10)(2, 10) on the graph.
  • Draw a straight line through these two points, which extends through the origin (0,0)(0, 0), since a regular pentagon with a side length of 0 would also have a perimeter of 0.

This line represents the proportional relationship y=5xy = 5x.

Would you like to see a visual graph of this relationship? I can generate it for you.

Here are 5 related questions:

  1. What would be the perimeter if the side length is 3 inches?
  2. What is the side length if the perimeter is 25 inches?
  3. How does the graph change if the relationship between side length and perimeter changes to y=6xy = 6x?
  4. If Ezra doubles the side length, how does the perimeter change?
  5. What is the slope of the line representing this relationship?

Tip: In proportional relationships, the slope of the line is the constant of proportionality, which is the factor by which one quantity scales the other.

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Math Problem Analysis

Mathematical Concepts

Proportional relationships
Geometry

Formulas

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Theorems

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Suitable Grade Level

Grades 6-8