In geometry, an angle is the shape of two rays separated by a common endpoint. The angle represents the angle between these two rays. The concept of obtuse angle is relative to acute angle and right angle. Acute angle is less than 90 degrees, right angle is equal to 90 degrees, and obtuse angle is greater than 90 degrees.

The upper limit of the obtuse angle is 180 degrees, because when two rays are on the same straight line with opposite directions, the included angle between them is 180 degrees, which is called a right angle. If the included angle is larger, then the two rays are no longer angled.

The degree range of obtuse angle is greater than 90 degrees but less than 180 degrees, just between acute angle, right angle and right angle, which makes obtuse angle a unique angle concept with clear mathematical and geometric significance.

The importance of learning mathematics;

Learning mathematics can cultivate people's logical thinking and problem-solving ability. Mathematics is a very logical subject, involving a lot of thinking activities such as reasoning, deduction and induction. By studying mathematics, we can exercise people's logical thinking ability and improve the agility and logicality of thinking.

Learning mathematics provides a foundation for the development of science and technology. Mathematics, as a universally applicable language, is an important foundation for the development of science and technology. Many important scientific and technological advances need the support of mathematics, such as computer science, physics, economics and so on. By studying mathematics, people can better understand the basic principles and laws of these disciplines and make greater contributions to the development of science and technology.

Learning mathematics can improve personal quality and competitiveness. In modern society, mathematics has become an indispensable skill, and mastering mathematical knowledge and skills has become an essential quality for many occupations. By studying mathematics, people can improve their mathematical literacy and professional competitiveness and better adapt to the development and changes of modern society.