Spanton, J. Humphrey (John Humphrey) · London, Macmillan and Co., Limited; New York, The Macmillan Company · leaf 27
b d e Fig. 22. If we multiply the base by half the altitude, we get the areaof a triangle ; or half its base by its altitude will give us thesame result. GEOMETRICAL DEFINITIONS. !3 Triangles of equal bases drawn between parallel lines areequal in area, and lines drawn parallel to their bases at… … Fig. 23. If we bisect two sides of a triangle and jointhe points of bisection, we get a line that isalways parallel to the third side (Fig. 24). Quadrilaterals.—If we bisect the foursides of a quadrilateral figure and jointhe points, it will always give us aparallelogram, as shown by dottedlines.…
Geometrical drawing · Design · Drawing
Internet Archive · Wellesley College Library · Public Domain Mark 1.0. Free to use for anything.
![An illustration from Clariss[imi] pictoris et geometræ Alberti Dureri, De varietate figurarum et flexuris partium ac gestib[um] imaginum, : libri duo, cqui priorib[us] De symmetria quondam editis, nunc primum in latinum conversi accesserunt (1534)](https://img.insideoutlibrary.com/img/200/ia-clarissimipictor00dure-26-24.webp)
