Practical plane and solid geometry for advanced students, including graphic statics, adapted to the requirements of the South Kensington syllabus (1899)
Harrison, Joseph, Baxandall, George Albert · London Macmillan · leaf 196
e. If this figure were given, then in order to determinefrom it the x co-ordinate of the point A, we should measurethe length of 01, ma, or na ; to ascertain the y co-ordinate,we should measure Om, la, or na; and for the z co-ordi-nate we should measure any one of On, On, ma, &&a. If it… … 7^7y so as to obtain the model of the planes of projection ; andto show the actual point A in space and the three per-pendiculars from it, we might use a small sphere with threeprojecting pieces of wire, Aa, Aa, An. The points a, a, and a are called the three projectionsof the point A. But some…
