第二章旋转与圆§7、旋转旋转是绕一定点转动一定角的运动。在这种变换下,平面上任一点和它的象点都与该定点等距离。若尺为绕一定点的旋转,P为平面上任意一点。可记为: R:P→P′P′为R之下点P的象。设R为绕原点的旋转,且R将A(1,0)映射成A′(c,s),另给一点B(x,0),由比例公式,点B的象为 Chapter 2 Rotation and Circle §7. Rotary rotation is a movement that rotates a certain angle around a certain point. In this transformation, any point on the plane and its image point are equidistant from the fixed point. If the ruler is a rotation around a certain point, P is any point on the plane. It can be written as: R:P→P’P’ is the image of point P below R. Let R be the rotation around the origin, and R maps A(1,0) to A’(c,s), and another gives B(x,0), from the proportional formula, the image of point B is