The tinman's manual and builder's and mechanic's handbook : designed for tinmen, japanners, coppersmiths, engineers ... with compositions and receipts for other useful and important purposes in the practical arts (1861)
Butts, I. R. (Isaac Ridler), 1795-1882 · Boston : I.R. Butts & Co. · leaf 39
34 TO CONSTRUCT THE FRUSTUM OF A CONE. SECTOR, FOR OBTAINING ANGLES.Fig. 22. « JL - … Sector, a portion of a circle comprehended between any tworadii and tlieir intercepted arcs.— Similar Sectors are those whoseradii include equal angles. To find the area of a sector. Say as 360 is to the degrees, &c.,in the arc of the sector, so is the area of the whole circle to the areaof the…
