Question

jenna reflected the triangle below across the x-axis . Describe her error

Answer 1

By definition, given a point (x,y), the rule for its reflection acrros the x-axis is:

$(x,y)\rightarrow(x,-y)$

You can see that the x-coordinate of the point (x,y) does not change,but the y-coordinate changes, because it has the opposite sign. For example, given a point (1,-2), its reflection across the x-axis would be:

$(1,-2)\rightarrow(1,2)$

When you see the picture of the reflection of the triangle ARP across the x-axis, you can identify Jenna's error: She didn't change the sign of the y-coordinates of the vertices of the triangle, but changed the sign of the x-coordinate of each one of them.