you draw a base line and then construct a perpendicular bisector to leave a 90° angle. To construct a 45° angle, first construct a perpendicular bisector of a line to leave a 90° angle.

The challenge consisted of climbing 999 steps at a 45 degrees angle. It began at the bottom of the Tianmen Mountain Road, which has a stairway and 99 dizzying turns. The hybrid SUV is the first ...