posted by Kristy on .
At noon, ship A is 180 km west of ship B. Ship A is sailing east at 40 km/h and ship B is sailing north at 30 km/h. How fast is the distance between the ships changing at 4:00 PM?
draw the right triangle.
start the origin at B at noon.
a is the distance ship A moves in 4 hours.
da/dt= + 40
b is the distance from the B starting point at noon.
dr/dt= 1/2 *1/(a^2+b^2)* (2a da/dt+2b db/dt)
solve for dr/dt
I tried plugging in the numbers for the variables, but I am not coming up with the right answer. I think the equation might be wrong.