1. The problem statement, all variables and given/known data 32) A stone dropped into a pond at time t=0 seconds causes a circular ripple that ravels out from the point of impact at 5 metres per second. At what rate (in square metres per second) is the area within the circle increasing when t=10? 2. Relevant equations I need to use the chain rule dy/dx = dy/du x du/dx 3. The attempt at a solution The area of a circle is A=∏r2 Differentiating this formula will tell me the rate at which the area increases for a specific radius dA/dr=2∏r The rate at which the radius increases is 5 metres per second, so I think that would be expressed as dr/dt=5m/s I need to find the rate of change of the area of the circle at 10 seconds. Using this chain rule, I think this would be found with dA/dt=dA/dr x dr/dt where dA/dt is the derivative of area as a function of time. So multiplying these derivatives gives me dA/dt=dA/dr x dr/dt =(2∏r)(5m/s) =(50∏rm)/s The radius at 10 seconds by multiplying 5m/s x 10s =50m. So I substitute 50m in for r. =(50∏(50m)m)/s =(2500∏m2)/2 I'm struggling a bit in my calculus class and I'm a bit unsure about all of this. Am I going in the right direction with my solution attempt above? Also I noticed on these forums that people are entering equations and formulas in "fancy text", if I may call it that. What I mean is making math stuff look like what one would see in a textbook, as opposed to using unicode characters like I did above. How can I do that?