formula method of periods by area and volume combined

例句：

1. 1.The formula for success is to set clear goals and work diligently towards them.
   成功的公式是设定明确的目标并努力实现它们。
2. 2. The scientist used a formula to calculate the mass of the sample.
   科学家使用一个公式来计算样品的质量。
3. 3. The engineer developed a new formula for the chemical reaction.
   工程师开发了一种新的化学反应公式。