上传内容为面积计算的c#源代码，主要是实现对常见的矩形、三角形、圆形等进行相应的面积运算-Upload content area of ​ ​ c# source code common rectangle, triangle, circle the appropriate area of ​ ​ operations

用C#设计一windows应用程序，，，按“A”画圆，按“B”画矩形，按“C”画三角形。-Design A Windows applications in C#, and, according to the A circle, rectangle according to the B picture, in accordance with the C draw A triangle.