To put this pentagon into parallel perspective inscribe the circle in which it is drawn in a square, and from its five angles 4, 2, 4, &c., drop perpendiculars to base and number them as in the figure. Then draw the perspective square (Fig. 217) and transfer these measurements to its base. From these draw lines to point of sight, then by their aid and the two diagonals proceed to construct the pentagon in the same way that we did the triangles and other figures. Should it be required to place this
pentagon in the opposite position, then we can transfer our measurements to the far side of the square, as in Fig. 218.
| Fig. 217. | Fig. 218. |
Or if we wish to put it into angular perspective we adopt the same method as with the hexagon, as shown at Fig. 219.
| Fig. 219. | Fig. 220. |
Another way of drawing a pentagon (Fig. 220) is to draw an isosceles triangle with an angle of 36° at its apex, and from centre of each side of the triangle draw perpendiculars to meet at o, which will be the centre of the circle in which it is inscribed. From this centre and with radius OA describe circle A 3 2, &c. Take base of triangle 1 2, measure it round the circle, and so find the five points through which to draw the pentagon. The angles at 1 2 will each be 72°, double that at A, which is 36°.