Aldis, W. Steadman (William Steadman), 1839-1928 · Cambridge [Eng.] Deighton, Bell, and co.; London, G. Bell and sons · leaf 19
jiven pUnie is equal to tJie length of the line multiplied by thecosine of the angle between the line and plane. If from the angular points of a triangle we draw perpen-diculars on a fixed plane the feet of these perpendiculars forma triangle whicli is called the projection of the given triangleon… … pendicular to RS, and PH and QL perpendicular to theplane RHS. Then RHL is equal to the projection of PQR onthe given plane. Join HK, then it follows, from Euclid, xi. 8, that RS isperpendicular to the plane PKH and therefore to KH.Hence PKH is the angle between the plane PQR and theplane on which…
