1. the problem goes like this : The energy of interaction of a classical magnetic dipole with the magnetic field B is given by E = −μ·B. The sum over microstates becomes an integral over all directions of μ. The direction of μ in three dimensions is given by the angles θ and φ of a spherical coordinate system The integral is over the solid angle element = sin θdθdφ. In this coordinate system the energy of the dipole is given by E = −μB cos θ. Choose spherical coordinates and show that the probability p(θ, φ)dθdφ that the dipole is between the angles θ and + dθ and φ and φ + dφ is given by p(θ, φ)dθdφ = (e^(μB cos θ) sin(θ) dθ dφ)/z 2. Relevant equations z = ∫∫ e^(μB cos θ) sin(θ) dθ dφ . 3. The attempt at a solution i have no idea what to do , and i tried all i know i know that the boltzmann distribution gives you the probability that a particle has an energy is : e^(μB cos θ)/∫e^(μB cos θ) , but how do i integrate the spherical coordinates i don t know . please help me and thank you .