The normal elementary geometry : embracing a brief treatise on mensuration and trigonometry : designed for academies, seminaries, high schools, normal schools, and advanced classes in common schools (1884)
Brooks, Edward, 1831-1912 · Philadelphia : Christopher Sower Co. · leaf 64
will4C* = AB* + BC\ For, construct squares on eachof the sides, draw BD parallel toAF and produce it to E, and draw B£the diagonals BF and HC. Thetwo triangles HA C and BAF areequal; for, AC equals AF, beingsides of the same square, HAequals AB, for the same reason,and the angle HAC equals the… … 60 GEOMETRY. also, since IB0 is a straight line, the triangle HAG andsquare ABIH have the same altitude; hence, the triangleis one-half of the square (Th. III.). But these two trian- gles BAF and HAG are equal; hence, the rectangle AFEBis equal to the square ABIH. In the same manner we mayprove…
Geometry · Plane trigonometry
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