If u=f(x, y) where x=(e^s)(cos(t)) and y=(e^s)(sin( show that (du/dx)^2 + (du/dy)^2 = (e^(-/ds)^2+(du/dt)^2))

Afarmer has decided to divide his land area in half in order to plant soy and corn. calculate the area of the entire area so he knows how much soil is needed. each bag of soil covers 20 square yards. how many bags should the farmer purchase? (4 points) 1 bag 2 bags 3 bags 4 bags