Final answer:
The constant of proportionality in the context of the perimeter of an equilateral triangle is determined by dividing the given perimeter by the length of a side. In this case, it is 17.7 ÷ 5.29, giving a constant of 3, corresponding to option D.
Step-by-step explanation:
The question asks to find the constant of proportionality for the perimeter of an equilateral triangle based on its side length. Since the perimeter (P) of an equilateral triangle is the sum of all its sides and each side is of equal length, we can write the equation as P = 3 × (length of one side). In this case, we know the perimeter is 17.7 when the length of one side is 5.29.
To find the constant of proportionality (k), we set up the equation 17.7 = k × 5.29. Solving for k gives k = 17.7 / 5.29. After completing the division, the result is k = 3. Therefore, the constant of proportionality when the perimeter is 17.7 and the length of a side is 5.29 is 3, which corresponds to option D.