Question

If you reflect triangle FGH across the y- axis what will be the coordinates of the vertices of the image triangle FGH?

Answer 1

4th Option is correct.

Explanation:

Given:

Coordinate of the vertex of the ΔFGH is F( -2 , -1 ) , G( 2 , 2 ) and H( 4 , -3 )

To find: Coordinate of the image of the ΔFGH (.i.e., ΔF'G'H' ) when ΔFGH is reflected over y-axis.

We know that when a point ( x , y ) reflected over y-axis , the y-coordinate remains the same but the x-coordinate is transformed into its opposite .i.e., ( -x , y )

So, Image of the Vertex F( -2 , -1 ) = F'( -(-2) , -1 ) = F'( 2 , -1 )

Image of the Vertex G( 2 , 2 ) = G'( -2 , 2 )

Image of the Vertex H( 4 , -3 ) = H'( -4 , -3 )

Therefore , 4th Option is correct.

Answer 2

Option D.

Explanation:

A reflection is a mirror image across the a line of reflection. The image will be perpendicular to the line of reflection and equal distance from it as the pre-image is too. This means that point G will move horizontally across the y-axis the same distance it is currently from the y-axis. It is 2 units away from the y-axis so G' will be 2 units on the other side or -2. This makes G' (-2,2). Notice this is the same coordinates of G only multiplied by -1. When reflecting a shape across the y-axis, the x-coordinates of the points are multiplied by -1.

So G (2,2) becomes (-2,2).

So F (-2,-1) becomes (2,-1).

So H (4,-3) becomes (-4,-3).