trigonometrical form of complex number

Some improved ways to the trigonometric function solutions that Cao made are discussed and improved, and some conditions of solutions with parameters restricted are supplemented,gaining some valuable results.

对Cao给出的三角函数形式的解做了进一步的讨论,提出了一些改进方法,对方程的解中的参数应满足的条件做了进一步补充说明,得到了一些有意义的结果。