ANSWER
C. Yes, their slopes have product -1
EXPLANATION
The slope of the line connecting
P(1,3) and Q(7,8) is
[tex] = \frac{8 - 3}{7 - 1} [/tex]
[tex] = \frac{5}{6} [/tex]
The slope of the line connecting
R(5,-7) and S(10,-13) is
[tex] = \frac{ - 13 - - 7}{10 - 5} [/tex]
[tex] = - \frac{6}{5} [/tex]
Product of the two slopes is
[tex] = \frac{5}{6} \times - \frac{6}{5} [/tex]
[tex] = - 1[/tex]
Since the product is -1, the slopes are perpendicular.
The correct answer is C.
