1. A computer readable storage medium for storing a graphics identification program to be executed by a computer for identifying a graphical shape of a trace drawn by a user on an input surface of an input device, wherein the graphics identification program causes the computer to execute: detecting the trace drawn on the input surface as coordinate points in chronological order; selecting coordinate points for representing the trace from among a group of the coordinate points in which the detected coordinate points are arranged in chronological order; calculating lengths of line segments obtained by connecting the selected coordinate points in chronological order; calculating, for each line segment, an absolute angle which the line segment forms with a previously determined reference straight line or a relative angle which the line segment forms with a line segment adjacent thereto; and comparing a trace graph in an orthogonal coordinate system, whose first axis indicates a distance from a starting point or an ending point of the selected coordinate points to each coordinate point along the line segment and whose second axis indicates an angle of the line segment whose startpoint is one of the selected coordinate points, with reference graphic graphs respectively representing a plurality of types of previously prepared reference graphics in the orthogonal coordinate system, and identifying a reference graphic represented by a reference graphic graph which most closely resembles the trace graph as a shape of the trace, wherein the graphics identifying further includes: calculating an area of a region surrounded by line segments which are not shared by the trace graph and the reference graphic graph in the orthogonal coordinate system for each reference graphic, and identifying a reference graphic having a smallest area among the areas calculated at the area calculating as a shape of the trace.