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 area, and then displayed on the screen.