Final answer:
The semicircle's diameter is 4 miles, calculated by using the perimeter of the semicircle and the approximation of π as 3.14.
Step-by-step explanation:
The student has asked, "The perimeter of a semicircle is 10.28 miles. What is the semicircle's diameter?" To solve this, first, we should recall that the perimeter P of a semicircle is half its circumference plus its diameter, which can be represented as P = (π × r) + 2r, where π represents the constant pi and r is the radius. Given that π is approximated as 3.14 for this problem, let's set up the equation with the known perimeter.
Therefore, we have 10.28 = (3.14 × r) + 2r, or simply 10.28 = (3.14 + 2) × r. Thus, 10.28 = 5.14 × r. Solving for r, we get r = 10.28 / 5.14, which gives us r = 2 miles. Since the diameter d is twice the radius, the semicircle's diameter is therefore d = 2 × 2 = 4 miles.