The coordinates of vertex B' is [tex]P'(x,y) = (-2, -8)[/tex].
A point if reflected across the line [tex]y = -2[/tex] by means of the following formula:
[tex]P'(x,y) = P(x,y)+2\cdot [(x_{P}, -2)-P(x,y)][/tex] (1)
Where:
If we know that [tex]P(x,y) = (-2,4)[/tex] and [tex]x_{P} = -2[/tex], then the coordinates of the vertex is:
[tex]P'(x,y) = (-2, 4) + 2\cdot [(-2,-2)-(-2,4)][/tex]
[tex]P'(x,y) = (-2, 4) +2\cdot (0, -6)[/tex]
[tex]P'(x,y) = (-2, 4) + (0,-12)[/tex]
[tex]P'(x,y) = (-2, -8)[/tex]
The coordinates of vertex B' is [tex]P'(x,y) = (-2, -8)[/tex]. [tex]\blacksquare[/tex]
To learn more on reflections, we kindly invite to check this verified question: https://brainly.com/question/1878272