Hi, I need some help understanding the solution to a problem. Equations: x = r.cos(θ) y = r.sin(θ) r = x2 + y2 theta = arctan(y/x) Question: Determine the Jacobian Matrix for (x,y)T and for (r, θ)T SOLUTION: I understand and can compute by myself the Jacobian for (x,y)T, but the solution to for J(r, θ) i dont understand. J(r,θ) = ( (@r/@x, @r/@y) , (@θ/@x, @θ,@y) )T Ok so that makes sense... Then they gave me this... (@r/@x, @r/@y) =( x / sqrt( x2 + y2 ) , y / sqrt(x2 + y2) ) Why isn't it just 2x and 2y respectively? why does it resemble something similar to a magnitude? thanks for your help.