1. The problem statement, all variables and given/known data The cross section of a trough for holding water is an inverted equilateral triangle. The trough is 6m long and 50cm deep. If the water is flowing in a t a rate of 0.6m^3/min, find the rate at which the height is changing when the water is 40cm deep. 2. Relevant equations implicit differentation 3. The attempt at a solution I started with the equation V=1/2(bh)l and the given information of dV/dt=0.6. From the equation and all information given, I can see that I am not given b as either a static number or as a rate, and thus need to somehow get rid of it by finding another relationship. My problem is I can't seem to find that relationship, as the only thing that seems to make sense to me is to use similar triangles to get a relationship, but I used this method I ended up with 3 variables instead of 2. Could anyone be of assistance and point me in the right direction for this question, as I have no idea where to find the correct equation for differentation to solve for the answer. Thanks in advance.