Refleksi terhadap y = mx + c dengan m = tan Theta
\(= \begin{pmatrix} \cos\theta & \sin\theta \\ \sin\theta & -cos\theta \end{pmatrix} \begin{pmatrix} x \\ y-c \end{pmatrix} \begin{pmatrix} x \\ y \end{pmatrix}\)
dimana
\(x' = x \cos 2 \theta + (y-c) \sin 2\theta \\
y' = x \sin 2\theta - (y-c) \cos 2\theta + c\)