25 percent. According to the query of the senior high school entrance examination network, in 2023, the content of the mathematical triangle in the senior high school entrance examination in Beijing accounted for 25%. Triangle is a piece of knowledge with the most content in junior high school geometry, and it is also a necessary basis for learning plane geometry well. It runs through the geometry knowledge of senior two to senior three. There are triangular questions (congruence, similarity, bisector of angle, perpendicular line, height line and right triangle solution), and quadrilateral questions (parallelogram, rectangle, diamond and square), accounting for one quarter of the total score.