diketahui titik A (4,5),tentukan bayangan akibat rotasi 90° dengan titik pusat O dan dengan titik pusat P(1,1)?

[tex] \left[\begin{array}{ccc}x'\\y'\end{array}\right] = \left[\begin{array}{ccc}cos90&-sin90\\sin90&cos90\end{array}\right] \left[\begin{array}{ccc}4-1\\5-1\end{array}\right]+\left[\begin{array}{ccc}1\\1\end{array}\right] [/tex]
= [tex]\left[\begin{array}{ccc}x'\\y'\end{array}\right] = \left[\begin{array}{ccc}0&-1\\1&0\end{array}\right] \left[\begin{array}{ccc}3\\4\end{array}\right]+\left[\begin{array}{ccc}1\\1\end{array}\right] [/tex]
= [tex]\left[\begin{array}{ccc}x'\\y'\end{array}\right] = \left[\begin{array}{ccc}-4\\3\end{array}\right]+\left[\begin{array}{ccc}1\\1\end{array}\right] [/tex]
= [tex]\left[\begin{array}{ccc}x'\\y'\end{array}\right] = \left[\begin{array}{ccc}-3\\4\end{array}\right][/tex]