Question

Suppose a triangle reflects over the y-axis. Which describes how the transformation affects the coordinates of the vertices?

A) (x, y) → (−x, y)
B) (x, y) → (−x, −y)
C) (x, y) → (x, −y)
D) (x, y) → (y, x)

Answer 1

a

Explanation:

Answer 2

Answer: OPTION A.

Explanation:

By definition:

- When you reflect a figure, you flip it over a line of reflection, then, both figures will be in opposite directions.

- The image (which is the reflection) and the pre-image will have the same shape ad size.

- If a figure is reflected over the y-axis, then the sign of the x-coordinate is changed.

Keeping the above on mind, you can conclude that when a triangle is reflected over the y-axis the coordinates of the vertices are afectted as following:

- The y-coordinate is not changed.

- The sign of the x-coordinate is changed.

Then:

`(x,y)` →
`(-x,y)`