An architect plans to make a drawing of the room of a house. the segment lm represents the ceiling of the room. he wants to construct a line passing through q and perpendicular to side lm to represent a wall of the room. he uses a straightedge and compass to complete some steps of the construction as shown..

Here are the steps

1: Put the compass on Q and make the width equal to the distance from Q to L. Extend line LM towards the left side of L and draw an arc hitting the line segment on the left side of L

2.  Without changing the width and position of the compass, draw an arc between L and M.

3. Without changing the width of the compass, put the compass on the point of intersection of the arc and line LM (left side of L). Draw an arc above line LM.

4. Without changing the width of the compass, put the compass on the point of intersection of the arc and line LM (right side of L). Draw an arc above line LM.

5. Use a straight edge to make a line from the intersection of the two arcs above line LM to Q intersecting through L along the way.