计数公式与时钟夹角公式在中学解题中的应用

The Application of the Formula of Count n(n- 1) /2 and Clock Angle| m × 30°- 5. 5°n | in Solving Middle School Mathematics Problem

本文应用计数公式n(n-1)/2和时钟夹角公式|m×30°-5.5°n|解决了两个元素确定一个图形或组合(握手、比赛等)的计数问题和与时针和分针夹角的相关数学问题。

The article solves the counting problem that two elements determine one graphic or combination （ handclasp ,concours and so on ） and the mathematical problem about the angle between the hour hand and minute hand through the application of the formula of count n （n-1）/2 and clock angle ｜m×30°-5.5°n｜.