Angle ∠BAC might refer to any of four angles: the clockwise angle from B to C, the anticlockwise angle from B to C, the clockwise angle from C to B, or the anticlockwise angle from C to B, where the direction in which the angle is measured determines its sign (see Positive and negative angles). However, in many geometrical situations it is obvious from context that the positive angle less than or equal to 180 degrees is meant, and no ambiguity arises. Otherwise, a convention may be adopted so that ∠BAC always refers to the anticlockwise (positive) angle from B to
Back-in angle parking in traffic delays and considerable risk of collisions with pedestrians, bicyclists, and vehicles. Existing pull-in angle parking spaces can be converted to back-in angle parking by re-striping to flip the angle of the stall markings. Streets with parallel parking have also been converted to back-in angle parking. In either case, the pavement markings are often augmented with signage indicating that vehicles must be backed in. According to the Pedestrian & Bicycle Information Center, back-in angle parking provides motorists with better vision of pedestrians, bicyclists, motor vehicles, and other road users as they exit a parking space and enter moving traffic.