编写一个 CMyPoint 类，然后在键盘输入两个点坐标，在屏幕显示该点距离，在键盘输入三个点，求出这三点组成的面积，然后在屏幕显示。-Write a CMyPoint class, and then enter the coordinates of two points on the keyboard, the screen displays the point distance, input three points on the keyboard, and the three points