Geometry (math)

Question

∆ABC was transformed according to the rule (x, y) → (x, −y) to create ∆A'B'C'. What transformation justifies the relationship between the triangles?

 A. A translation 1 unit to the right and 1 unit down justifies ∆ABC ≅ ∆A'B'C'. 

B. A rotation of 90° counterclockwise justifies ∆ABC ≅ ∆A'B'C'. 

C. A reflection over the x-axis justifies ∆ABC ≅ ∆A'B'C'.

D.  A reflection over the y-axis justifies ∆ABC ≅ ∆A'B'C'.

Answer 1

(x,y) to (x,-y) is a reflection about the x axis

1 unit right and 1 down transforms

f(x) to f(x-1)-1

a reflection over the x axis transforms (x,y) to (x,-y)

or

transforms f(x) to -f(x)

reflection over the y axis transforms (x,y) to (-x,y)

or

transforms f(x) to f(-x)