1. The problem statement, all variables and given/known data A balloon is rising at a constant speed of 5 ft/s. A boy is cycling along a straight road at a speed of 15 ft/s. When he passes under the balloon, it is 45 ft above him. How fast is the distance between the boy and the balloon increasing 3 seconds later. 2. Relevant equations dx/dt=15 ft/s dy/dt=5 ft/s c2=x2+y2 3. The attempt at a solution 2c dc/dt = 2x dx/dt + 2y dy/dt c(dc/dt) = x(dx/dt) + y(dy/dt) c(dc/dt) = x(15) + y(5) c(dc/dt) = 15x + 5y My first problem is: Is the 45ft x or y?