Figure 3 shows the front and top views of a block with an inclined face (dimensions in mm). A Ø20 hole is drilled square to the inclined face at its centre. A partial auxiliary view is drawn to show the true shape of the inclined face. Determine (a) the angle between the auxiliary reference line X_{1}Y_{1} and XY (answer in °) and (b) the true area of the inclined face, excluding the hole (answer in mm²).