bayangan dari titik A(-2,5) jika diputar terhadap titik (1,2) dengan sudut putar)-90 derajat adalah

titik A(-2,5) dirotasi 90° terhadap titik (1,2)

[tex]A' = \left[\begin{array}{ccc}cos 90&-sin 90\\sin 90&cos 90\end{array}\right] \left[\begin{array}{ccc}-2-1\\5-2\\\end{array}\right] + \left[\begin{array}{ccc}1\\2\end{array}\right][/tex]
[tex]A' = \left[\begin{array}{ccc}0&-1\\1&0\end{array}\right] \left[\begin{array}{ccc}-3\\3\\\end{array}\right] + \left[\begin{array}{ccc}1\\2\end{array}\right][/tex]
[tex]A' = \left[\begin{array}{ccc}-3\\-3\\\end{array}\right] + \left[\begin{array}{ccc}1\\2\end{array}\right][/tex]
[tex]A' = \left[\begin{array}{ccc}-2\\-1\\\end{array}\right][/tex]

maka petanya A'(-2,-1)