The carpenter and joiner's assistant : being a comprehensive treatise on the selection, preparation, and strength of materials, and the mechanical principles of framing, with their application in carpentry, joinery, and hand-railing : also, a course of instruction in practical geometry, geometrical lines, drawing, projection, and perspective : and an illustrated glossary of terms used in architecture and building (1860)
Newlands, James, 1813-1871 · Glasgow : Blackie and Son · leaf 30
gon being given, to describe another leaving the same area, but a different number of sides. Suppose the given polygon to be a regular pentagon: let it be required to describe a regular nonagon, the area of which shall be equal to that of the pentagon (Fig. 108, given polygon: bisect any two of its… … nine equal parts, and make D E (no. 2) equal to five of these the base of the elementary triangle, applied successively parts ; then upon D E, as a base, construct the triangle to the circumference, will produce a decagon having the D e n, having its altitude or perpendicular height equal
