9514 1404 393
Answer:
the lines are perpendicular
Explanation:
You can tell something by looking at the differences of coordinates:
B-A = (6-2, -11-5) = (4, -16) . . . . . Δy/Δx = -16/4 = -4
D-C = (-1-3, 9-10) = (-4, -1) . . . . . Δy/Δx = -1/-4 = 1/4
The product of the slopes of these lines is (-4)(1/4) = -1, so ...
the lines are perpendicular