1. The problem statement, all variables and given/known data For the transformation, draw the lattice lines, calculate the derivative, and calculate the Jacobian. [itex]x=rcos\theta[/itex] [itex]y=rsin\theta[/itex] 3. The attempt at a solution I drew the lattice lines correctly. What I am confused about is the derivative. Since x and y are both functions of r and theta, what derivative are they talking about? Wouldn't I have to take the partial with respect to R or theta? This section is supposed to be on calculating determinants. I understand that the Jacobian is the determinant of a particular matrix, but where does this matrix come from?