For problem: See Attachment I've never done a problem of this sort and it's proving to be much more difficult compared to the other problems I have had assigned to me. I'm not entirely sure which formulas to use but I've been playing with the following: Length of Arc = r[itex]\theta[/itex] A = [itex]\pi[/itex]r^2 C = [itex]\pi[/itex]d = 2[itex]\pi[/itex]r A of Sector= 1/2([itex]\theta[/itex]-Sin[itex]\theta[/itex])r^2 And the Cosine Law Being honest, I'm a little confused by the question. I'm not entirely sure if I labelled my variables correctly. But I made a diagram and this is what I did so far: - L = r[itex]\theta[/itex] So: dL/dt = dr/dt x d[itex]\theta[/itex]/dt I assumed the walking speed on the surface was dL/dt. Therefore, dL/dt = 4. I assumed d[itex]\theta[/itex]/dt = 4 m/s x 2[itex]\pi[/itex] rad/m = 8. Therefore, I was able to calculate that dr/dt = 1/2. I differentiated the cosine formula just to give myself a general idea of what I had to work with, but with two variable side lengths and an unknown [itex]\theta[/itex] I was at a loss. Note: After quite a bit of searching, this was the closest value I found to help me out. But in this example, a value for theta is given and two side lengths are known. I think my main problem may be understanding the question. If someone could clarify it and give me some pointers that would be great! Thanks!