I have a question about #8,
The question tell you that the rate that the side of an equalaterial triangle is decreasing at is 2cm/s and that you have to find the rate the area is decreasing when it is 100cm^2.
I assumed that you would use the equation that finds the area of an equalaterial in relation to the side but I keep getting a different answer
Any suggestions as to where I'm messing up would be very much appreciated.
I'm going to give a couple of points that helped me with related rates.
1. Related rates are terrible, crying is acceptable.
b. Choose variable names that are less similar, for example A for area and S or x or whatever for side length, it will make things less confusing in the future, trust.
Γ . Derive your own formula for A, and from that, find the length of a; Special triangles bro.
4. Show as much work as you can, when it comes down to Related Rates questions, sometimes it's those part marks that pull you through.
V. Keep your answers in exact form, this isn't Physics class. No approximations (Personal pet peeve).
Upon brief inspection, it appears that the given answer is incorrect. In your solution, however, don't forget that da/dt is -2...this value should be substituted and multiplied to get the answer. Also, I'm not sure how you got 37.224. After including the -2 for da/dt, the answer should work out to roughly -26..3 cm^2/s. Lastly, I'm assuming you looked up the formula for the area of an equilateral triangle. Could you come up with it on your own, if needed (I know you could!)?