What is the Jacobian ∂(x,y)∂(r,θ)\frac{\partial(x, y)}{\partial(r, \theta)}∂(r,θ)∂(x,y) for the transformation x=rcosθx = r \cos \thetax=rcosθ and y=rsinθy = r \sin \thetay=rsinθ?
rrr
1/r1/r1/r
r2r^2r2
−r-r−r