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
Straight razor as heavy stropping and honing. Shaving is done with the blade at approximately an angle of thirty degrees to the skin and in a direction perpendicular to the edge; an incision requires the movement of the blade to be sideways or in a direction parallel to the edge. These circumstances are always avoided by the shaver, who always shaves in a direction perpendicular to the cutting edge of the blade. To be most effective, a straight razor must be kept extremely sharp. The edge is delicate, and inexpert use may bend or fold over the razor's edge. To unfold and