1.广义极坐标为了确定平面上点的位置,通常采用直角(即笛卡儿)坐标釆。在这里,我們研究确定平面上点的位置的另一种方法。在平面上取某一点O(图1),称它为极点;从这点引出任一射线OP,称它为极軸。 現在我們想确定某一点M的位置。显然,平面上任一点(除极点之外)都在通过极点的某唯一射线上,点M就在射綫OM上。这条射綫的位置可以用它与极軸的夹角来确定。这个角叫做极角。我們规定,由极轴沿逆时針方向計 1. Generalized Polar Coordinates In order to determine the position of a point on a plane, a Cartesian coordinate system is usually used. Here, we study another way to determine the position of a point on a plane. Take a point O (Fig. 1) in the plane and call it the pole; from this point lead out any ray OP and call it the polar axis. Now we want to determine the position of a certain point M. Obviously, any point on the plane (except the pole) is on a certain ray passing through the pole, and point M is on the ray OM. The position of this ray can be determined by its angle with the polar axis. This corner is called polar angle. We specify that the polar axis be counterclockwise