Fig. 122.
Ex. 17.—To construct a parallelogram of which the sides and one of the angles are given, [Fig. 122]. Draw the side D E equal to the given length A, and set off the other side D F equal to the other length B, forming the given angle C. From E with D F as radius, describe an arc, and from F, with the radius D E cut the arc at G. Draw F G, E G. Or, the remaining sides may be drawn as parallels to D E, D F.
Fig. 123.
Ex. 18.—To describe a circle about a triangle, [Fig. 123]. Bisect two sides A B, A C of the triangle at E F, and from these points draw perpendiculars cutting at K. On the center K, with the radius K A draw the circle A B C.
Fig. 124.
Ex. 19.—To describe a circle about a square, and to inscribe a square in a circle, [Fig. 124].
First. To describe the circle. Draw the diagonals A B, C D of the square, cutting at E; on the center E with the radius E A describe the circle.