Question

Triangle `JAR` has vertices `J(1,4), A(3,5)` and `R(2,1)`. If you reflect triangle `JAR` across the `y`-axis, what will the coordinates of the vertices of the image triangle `J'A'R'` be?

Answer 1

`f(1, 4) = (-1, 4)`

`f(3, 5) = (-3, 5)`

`f(2, 1) = (-2, 1)`

Explanation:

Reflection is a function of 2 variables which returns 2 variables.

`f((x),(y)) = ((-x), (y)) = ((-1, 0), (0, 1)) * ((x), (y))`