现将圆内角定理和圆外角定理及其部分应用介绍如下·一、圆内角定理“顶点在圆内的角的度数,等于它所对的弧和它的对顶角所对的弧的度数的和的一半·”(初中几何第二册19页的第1题)二、圆外角定理“顶点在圆外、两边和圆相交的角的度数,等于这个角的两边所夹的两条弧的度数的差 Now, the inside angle theorem and the outside corner theorem and some of their applications are described as follows. First, the inside angle theorem of the circle “The degree of the angle of the vertex in the circle is equal to the degree of the arc of the arc it is facing against and its vertex angle. Half of Harmony" (secondary geometry in Volume II, Page 19, Problem 1) 2. Theorem of Outer Circles Theorem: The degree of the vertex whose vertex is outside the circle and the sides intersect with the circle is equal to the two arcs sandwiched by the two sides of this angle. The difference in degrees