5: Perpendicular lines Last updated Save as PDF Page ID 23611 Anton Petrunin Pennsylvannia State University 5.1: Right, Acute and Obtuse Angles 5.2: Perpendicular Bisector 5.3: Uniqueness of a perpendicular 5.4: Reflection across a line 5.5: Perpendicular is shortest 5.6: Circles 5.7: Geometric constructions