Question

identifying types of lines in three - a and c which are l which are perpendicular lines? which are skew lines?

Explanation:

Step1: Recall definition of skew lines

Skew lines are non - parallel and non - intersecting lines in 3 - D space.

Step2: Analyze given lines

Lines that are not in the same plane and do not intersect or are parallel are skew. From the figure, if we assume the planes and the positions of the lines correctly, lines that are in different non - parallel planes and do not intersect are skew. For example, if line $a$ is in one plane and line $d$ is in another non - parallel plane and they do not intersect, they are skew.

Answer:

$a$ and $d$ (assuming based on typical 3 - D line relationships in the figure; without more specific information about the lines' exact positions relative to the planes, this is a general answer based on the concept of skew lines)