Please find diagram attached
Answer and explanation:
Perpendicular lines are lines that meet at 90 degrees/ right angle.
The question seems to be incomplete but I will explain what perpendicular lines are in the context of lines lll and mmm, with some assumptions about the lines.
Assume that line III is 30mm long and line mmm is 25mm long, we say that line III is perpendicular to line mmm if line III meets line mmm at 90 degrees as we see in the diagram attached.