Perpendicular Line
To draw a perpendicular line:
1. Click Line in Geometry.
2. Click Perpend in Line.
3. Click the existing line.
4. Specify the point from which the perpendicular line should be dropped.
Alternatively:
1. Click Perpend.
2. Click the existing line.
3. Specify a point on the existing line.
4. Enter the length of the perpendicular line. If the perpendicular line appears on the wrong side of the line, repeat the operation using the opposite sign for the entered value.