Which file shape is ideal for creating internal angles and corners?

The triangular file is ideal for creating internal angles and corners because its pointed shape allows for precision in sharpening or defining these features. The three sharp edges of a triangular file can easily reach into tight spaces, making it effective for work that requires the formation of acute angles and intricate corner details. This is particularly useful in metalworking and woodworking applications where such angles are common.

Other file shapes serve different functions: a flat file is suitable for flat surfaces, a round file excels in enlarging or smoothing holes, while a half-round file offers versatility with both flat and rounded edges but lacks the precision needed for sharp corners. Thus, the triangular file stands out as the most appropriate choice for tasks involving internal angles and corners.