DIAGRAM 78.—This diagram is laid out to and must be enlarged by inches. Draw lines O 4 and O G. O to 1 is 5 inches. From 1 to 4, the side length, is 43 inches. From 1 to 2 is 3 inches. O to A is 10 inches. A to B is 3¾ inches. B to C is ¾ inch.