https://www.math.ryukoku.ac.jp/~tsutomu/LA1/10/lecture1006.pdf6 2 2 x y 2 2 2 x y 2 2 2 6.1 t PP = P t P = I P P P 2 ( −1 0 0 1 ) , ( 1 0 0 −1 ) , ( cos θ − sin θ sin θ cos θ ) , ( cos θ sin θ sin θ − cos θ ) y x θ x θ P x y (Px, Py) =t (Px)(Py) = t x(t PP)y = t xy = (x, y) (6.1) x = y 2 Figure 6.1 θ x y θ′ , , P P θ θ ′ = = = x x y y P Py Px Figure 6.1: 84 6.2 n P j vj j = 1, 2, · · · , n t PP = t v1 t v2 . . . t vn ( v1 v2 · · · vn ) =
