$6-38.1$h cartesian coordinates,

hat$(L{)}_z=-i(x\frac{\text{d}\text{e}\text{l}}{\text{d}\text{e}\text{l}\text{y}}-y\frac{\text{d}\text{e}\text{l}}{\text{d}\text{e}\text{l}\text{x}})$

oblems

Convert this equation to spherical coordinates, showing that

hat$(L{)}_z=-i\frac{\text{d}\text{e}\text{l}}{\text{d}\text{e}\text{l}}$