If in a triangle ABC: Cos A + Cos B + Cos C = 3/2 then what is so special about this triangle?

special about this triangle is that may be it's equilateral triangle , i.e cos60+cos60+cos60=3/2

If P=Sin A.Sin B, Q= Sin C.Cos A, R = Sin A.Cos B and S=Cos A.Cos C then 5(P^2+Q^2+R^2+S^2) = ??