Given that the triangle ABC is at A = ( 5, 5 ) B = ( 2, 8 ) C = ( 9, 7 ), and if the triangle is reflected across the line y = 3, find the new position of point C'.

Answer:
A. (9, -1)
Explanation:
Given the triangle ABC, the coordinate of point C is:
[tex]C=(9,7)[/tex]We want to reflect C across the line y=3.
Comparing the y-coordinate of C and the given line:
[tex]\begin{gathered} 3+x=7 \\ 3+4=7 \\ \implies x=4 \end{gathered}[/tex]Since the point and its image must be the same distance from the line of reflection, the y-value of the image point, C' will be:
[tex]3-4=-1[/tex]Thus, the new position of C' will be:
[tex]C^{\prime}=(9,-1)[/tex]Option A is correct.