Titik (10,5) dicerminkan terhadap garis y = 3,akan menghasilkan bayangan titik

Pencerminan terhadap garis y = b
x' = x
y' = 2b - y

(10,5)  dicerminkan ke y = 3
x= 10,. y = 5 , b = 3
x' = x = 10
y' = 2b -y = 2(3) - 5 = 6-5 =1

(x',y') = (10, 1)