A toroid having a cross section of rectangular shape is defined by the following surfaces: the cylinders ρ = 2 and ρ = 3 cm, and the planes z = 1 and z = 2.5 cm. The toroid carries a surface current density of −50a_z A/m on the surface ρ = 3 cm. Find H at the point P(ρ, ϕ, z):

(a) P_A(1.5 cm, 0, 2 cm);

(b) P_B(2.1 cm, 0, 2 cm);

(c) P_C(2.7 cm, π/2, 2 cm);

(d) P_D(3.5 cm, π/2, 2 cm).