《中学数学》刊登的“一类三角题的复数解法”一文介绍了复数在三角方面的一些应用。笔者试作如下补充。(原文见1985年2月号) 设z=cosθ+isinθ,z=cosθ-isinθ。显然有z·z=1。易求得sinθ=z-z/2=z~2-1/2iz,cosθ=z~2+1/2z,tgθ=z~2-1/i(z~2+1),由棣美弗公式 The article “Complex Solutions to a Class of Trigonal Questions” published in “Middle School Mathematics” describes some applications of complex numbers in terms of triangles. I try to add as follows. (For the original version, see February 1985.) Let z = cosθ + isinθ and z = cosθ - isinθ. Obviously z z=1. Easy to find sinθ=z-z/2=z~2-1/2iz, cosθ=z~2+1/2z, tgθ=z~2-1/i(z~2+1)