Haswell's engineers' and mechanics' pocket-book .. (1844)
Haswell, Chas. H. (Charles Haynes), 1809-1907 · New York, Harper & brothers · leaf 67
OF FOUR-SIDED FIGURES2. a ■ … To find the Area of a four-sided Figure, v)hether it be a Square, Paral-lelogram, Rhombus, or a Rhomboid.Rule.—Multiply the length by the breadth or perpendicular height,and the product will be the area. OF TRIANGLES. To find the Area of a Triangle^figs. 5 and 6, r c 6.
Engineering · Mechanical engineering
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.