Math Problem Statement

If you increase each side length in a triangle by 5%, does this increase the perimeter by 5%? Explore and write up your findings.

Solution

To explore whether increasing each side of a triangle by 5% results in a 5% increase in the perimeter, let's break down the problem systematically.

Step 1: Define the triangle and its perimeter

Let the original side lengths of the triangle be aa, bb, and cc. The perimeter PP of the triangle is the sum of its side lengths:

P=a+b+cP = a + b + c

Step 2: Increase each side length by 5%

When we increase each side length by 5%, the new side lengths become:

New side length of a=a×(1+0.05)=1.05a\text{New side length of } a = a \times (1 + 0.05) = 1.05a New side length of b=b×(1+0.05)=1.05b\text{New side length of } b = b \times (1 + 0.05) = 1.05b New side length of c=c×(1+0.05)=1.05c\text{New side length of } c = c \times (1 + 0.05) = 1.05c

Step 3: Calculate the new perimeter

The new perimeter, PP', is the sum of the increased side lengths:

P=1.05a+1.05b+1.05cP' = 1.05a + 1.05b + 1.05c Factor out the 1.05:

P=1.05(a+b+c)P' = 1.05(a + b + c)

Step 4: Compare the new and old perimeters

We know that the original perimeter P=a+b+cP = a + b + c. Substituting this into the equation for the new perimeter:

P=1.05PP' = 1.05P

Step 5: Conclusion

From the equation P=1.05PP' = 1.05P, we can see that the new perimeter is 1.05 times the original perimeter. This shows that the perimeter increases by exactly 5% when each side length is increased by 5%.

Findings:

  • When each side of a triangle is increased by 5%, the perimeter of the triangle also increases by 5%.
  • This result holds true regardless of the shape of the triangle or the relative lengths of the sides, as the perimeter is a linear function of the side lengths.

Do you want any more details or have questions?

Here are 5 questions to expand on this topic:

  1. What happens to the area of a triangle when all sides are increased by 5%?
  2. Does this linear relationship between side lengths and perimeter hold for other polygons?
  3. How does increasing one side by 5%, while keeping others constant, affect the perimeter?
  4. How does this principle apply to geometric figures like circles or squares?
  5. What happens if you increase side lengths by different percentages?

Tip:

When working with proportional changes in geometric figures, always check whether the property (like area or perimeter) depends linearly or non-linearly on the dimensions.

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Math Problem Analysis

Mathematical Concepts

Geometry
Proportions
Perimeter

Formulas

Perimeter of a triangle: P = a + b + c
Increased side length formula: New side = Original side × (1 + Percentage Increase)
New perimeter: P' = 1.05P

Theorems

Linear relationships in proportions

Suitable Grade Level

Grades 8-10