Protractor

摘要

A protractor comprising a frame and a lever arm coupled thereto. The frame includes a first substantially straight edge and an elongate track adjacent to the first edge. The lever arm includes a second substantially straight edge and a channel which mateably engages the track of the frame. The channel/track combination couples the lever arm to the frame and permits the lever arm to rotate about an axis substantially orthogonal to the first and second edges. The first and second edges intersect at a point allowing a user to describe an angle between the two edges.