Blood pattern analysis is a technique that analyzes the size, location, shape, and distribution of blood pattern distributed at the scene of the incident to reveal the cause of the bleeding, and reconstructs a series of actions in chronological order. At the site of the bloodshed, gush, cast-off, impact spatter, expectorate, which are blood marks caused by projected, are observed in the classification system by the generation mechanism. In order to find the area of the origin of these bloodstains and to reconstruct the site, analysts are training using laser protractors and string connections or using a program called Hemospat to find the convergence point of the space, which is the price position. This study ignored gravity and air resistance, and compared the error value of using the triangular function and Spatter Angle app with using the Hemospat program. As a result of the study, when using the triangular function and Spatter Angle app, error value is derived to be less than 2 cm if the distance is less than 40 cm and the height is less than 120 cm.