Question

Select the correct answer. You reflect triangle PQR, with vertices P(-2, -4), Q(-3, -1), and R(-4, -4), across the y-axis to get triangle P′Q′R′. What are the coordinates of triangle P′Q′R′?

Answer 1

Since we have reflected only across the y-axis we know the x-values stay the same (but since they are changing quadrants will become positive) and the same goes for the y-values. Only the negative/positive area will change. Lets get to work:

P(-2, -4) will become P'(2, -4)

Q(-3, -1) will become Q'(3, -1)

R(-4, -4) will become R'(4, -4)

After doing this for a while you will be able to find the reflected coordinates without any trouble or graph.

Key point: Values stay the same