| 摘 要： | Let ξ=f(z) be a K-quasiconformal mapping (K-Q.C.) in the complex plane, f(∞)=∞. The image of the real axis under ξ=f(z) is a quasicirclz and the points ξ=f(z) and ξ=f(z) are a pair of symmetric points of the circle, we know that the connection between the quasicircle and the quasiconformal extention is essential. The distortion estimates of the quasicircle and of the symmetric points are both interesting. It is known that there exist two constants C_1(K) and C_2(K), depending on K oniy, such that the inequality
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