Science and art drawing : complete geometrical course ; consisting of plane and solid geometry, orthographic and isometric projection, projection of shadow's the principles of map projection, graphic arithmetic and graphic statics (1895)
Spanton, J. Humphrey (John Humphrey) · London : Macmillan · leaf 42
Fig. 49. Problem 15. To trisect any angle ABC.-*^ Erom B, with any radius, describe the arc AHC ; bisect theangle ABC; join A and C; with Das centre, and with DA as radius,describe the semicircle AGC; andwith the same radius, describe thearcs E and E from A and C; joinAG; take the length AG and set… … TRIANGLES. Problem 16. To construct an equilateral triangleon a given line AB. With A and B as centres, and withAB as radius, describe arcs cutting eachother at C; join C with A and B. ThenABC will be an equilateral triangle. ^ This is one of the impossibilities of geometry ; but this problem,…
Geometrical drawing
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