Answer:
[tex]r = 1036.725\,mi[/tex]
Step-by-step explanation:
The distance per unit grade on Earth is:
[tex]\Delta s = \frac{2\pi\cdot (3960\,mi)}{360}[/tex]
[tex]\Delta s \approx 69.115\,miles[/tex]
The distance between Pittsburgh and Miami is:
[tex]r = (69.115\,mi)\cdot (40.5^{\textdegree}-25.5^{\textdegree})[/tex]
[tex]r = 1036.725\,mi[/tex]