The hyperbolic trigonometric functions are to hyperbolae as the trigonometric functions are to circles. That is, imagine you plot these points on a Cartesian plane for all possible values of t.
双曲三角函数就是对曲线应用三角函数，也就是说，想象将这些点放在笛卡尔平面上来得到t的所有可能值。
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We recall the characteristics of the groups with hyperbolic symmetry and improve the IFS iterated function systems which are used to construct the classical fractal sets in the Euclidian plane.