Beginners are more difficult. For some students with poor mathematical foundation, Pythagorean theorem may be somewhat difficult. They may need to spend more time and energy to understand this theorem, and may involve more knowledge points, such as acute trigonometric function and right triangle, which need to be applied together with Pythagorean theorem. In addition, Pythagorean theorem has a wide range of applications, which can be combined with geometry, algebra and other disciplines, and may be difficult for beginners. For some students with good mathematical foundation, Pythagorean theorem may not be difficult, and they can easily understand and apply this theorem.