Reflections: find the coordinates
Key Notes :
A reflection flips a figure across a line to create a mirror image.
When a point is reflected across the y-axis, the x-coordinate changes sign.
Learn with an example
The point G(–4, –1) is reflected across the y-axis. What are the coordinates of the resulting point, G′?

Start with the point G(–4, –1) and the y-axis.

Reflect the point across the line.

Since G is 4 units to the left of the y-axis, G′ is 4 units to the right of the y-axis. G′ has coordinates (4, –1).
The point E(1, 2) is reflected across the x-axis. What are the coordinates of the resulting point, E′?

E ‘=(____ , ____)
Start with the point E(1, 2) and the x-axis.

Reflect the point across the line.

Since E is 2 units above the x-axis, E′ is 2 units below the x-axis. E′ has coordinates (1, –2).
The point E(–2, –6) is reflected across the y-axis. What are the coordinates of the resulting point, E′?

Start with the point E(–2, –6) and the y-axis.

Reflect the point across the line.

Since E is 2 units to the left of the y-axis, E′ is 2 units to the right of the y-axis. E′ has coordinates (2, –6).
let’s practice!