Question 467078
the courses of the two boats form a right triangle with the 85 mi separation being the hypotenuse


the eastbound boat is 7 mph faster for 5 hr, so it travels 35 mi more than the southbound boat


if d is the southbound distance, by Pythagoras ___ d^2 + (d + 35)^2 = 85^2


2d^2 + 70d + 35^2 - 85^2 = 0 ___ d^2 + 35d - 3000 = 0 ___ (d + 75)(d - 40) = 0


d + 75 = 0 ___ d = -75 , negative value not realistic


d - 40 = 0 ___ d = 40 ___ 40 mi in 5 hr is 8 mph