Const PI = 3.141516
Picture1.Cls
Picture1.Line (600, 100)-(3100, 100)
Picture1.Line (100, 600)-(100, 3100)
Picture1.Line (3600, 600)-(3600, 3100)
Picture1.Line (600, 3600)-(3100, 3600)
Picture1.Circle (600, 600), 500, , PI / 2, PI
Picture1.Circle (3100, 600), 500, , 0, PI / 2
Picture1.Circle (3100, 3100), 500, , 3 * PI / 2, 0
Picture1.Circle (600, 3100), 500, , PI, 3 * PI / 2