Dividing one equation by the other shows that the glide angle is given by tan θ = CD/CL. The performance characteristics of most interest in unpowered flight are the speed across the ground, Vg say, and the sink speed Vs; these are displayed by plotting V.sin θ = Vs against V.cos θ = Vg. Such plots are generally termed polars, and to produce them the glide angle as a function of V is required.[10]