Angle of repose is defined as the angle of the inclined plane with horizontal such that a body placed on it just begins to slide.
By definition, is called the angle of repose.
In limiting condition F = mg sin α and R – mg cos α
So F/R = tan α
∴ FR = μs = tanθ = tan α [As we know F/R = μs = tan θ]
Thus the coefficient of limiting friction is equal to the tangent of angle of repose.
As well as = i.e. angle of repose = angle of friction.