Answer:
b / (a+c) * b / (a-c) = -1
Explanation:
Perpendicular lines have slopes that multiply to -1
The slope of AC is
(b-0)/(a- -c)
b / (a+c)
The slope of BC is
(b-0)/(a -c)
b / (a-c)
If the lines are perpendicular then the slopes multiply to -1
b / (a+c) * b / (a-c) = -1