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一、基本概念 由圆上一点向圆的任意方向作射线,射线被圆周所截得的弦叫做射弦,圆上这点叫做射点。以射弦为半径的圆叫做射圆。 显然最长的射弦为圆的直径,长度为零之射弦即缩为射点。 二、定理 1.射圆之面积等于射弦所对弧(劣弧或半弧)以圆直径(过射点)为轴旋转所形成的球冠面积。以公式表示S_(球冠MON)=πL~2(L表示射弦长,MON如图1所示)。
First, the basic concept From the circle point to the circle in any direction for the ray, the ray is cut by the circle of the string is called the string, the circle on this point called the shooting point. A circle with a radius of a shot is called a round. Obviously, the longest shot string is the diameter of the circle, and the length of the shot string is reduced to the shot point. 2. Theorem 1. The area of the circle is equal to the area of the spherical cap formed by rotating the arc diameter (overshoot) on the axis of the arc (Arc or semi-arc). Formula S_ (sphere MON) = πL ~ 2 (L represents the shot length, MON shown in Figure 1).