normal approximation

例句：

1. 1. The engineer used a normal approximation to estimate the time for the project.
   工程师使用正常近似来估计项目的时间。
2. 2.In mathematics, a normal approximation is often used to solve equations involving trigonometric functions.
   在数学中，常使用正常近似来解决涉及正弦函数的方程。
3. 3.The normal approximation is a useful tool for quickly calculating the area of a circle.
   正常近似是一个快速计算圆面积的工具。