Question

The triangle ABC, where A is (2, 6), B is (-3, 5) and C is (4, 7), is reflected in the y-axis to triangle A'B'C'. Triangle A'B'C' is then reflected in the origin to triangle A" B" C".

(i) Write down the co-ordinates of A", B" and C".

(ii) Write down a single transformation that maps triangle ABC onto triangle A" B" C".

Answer 1

(i) Reflection in y-axis is given by M_y (x, y) = (-x, y)
∴ A’ = Reflection of A (2, 6) in y-axis = (-2, 6)
Similarly, B’ = (3, 5) and C’ = (-4, 7)
Reflection in origin is given by M_O (x, y) = (-x, -y)
∴ A” = Reflection of A’ (-2, 6) in origin = (2, -6)
Similarly, B” = (-3, -5) and C” = (4, -7)
(ii) A single transformation which maps triangle ABC to triangle A”B”C” is reflection in x-axis.