Osgood, William F. (William Fogg), 1864-1943, Graustein, William C. (William Caspar), 1888-1941, joint author · New York : The Macmillan Company · leaf 356
THE PLANE 337 EXERCISE Show that the equations of the inverse of the reflection (1)[or (2)] are precisely of the same form as the equations of thereflection. A transformation for which this is true is said tobe involutory. 5. Simple Elongations and Compressions. Let the plane bestretched directly… … More generally, if a pointP: (x, y) is to be carried to I timesits original distance from the axisof X, where I may have any positive constant value, not unity,the transformation will be given by the formulas: Fig. 8 (1) I x^ = X, \y = iy- When I is greater than unity, these formulas represent…
