A 60-cm-square section of panel heater is installed in the corner of the ceiling of a room having a 2.7-m × 3.6-m floor area with an 2.4-m ceiling. If the surface of the heater, made from oxidized iron, is at 147°C and the walls and the air of the room are at 20°C in the steady state, determine
(a) The rate of heat transfer to the room by radiation,
(b) The rate of heat transfer to the room by convection (h_c ≈ 11 W/m² K)

(c) The cost of heating the room per day if the cost of electricity is 7 cents per kW h