OPEN "input.txt" FOR INPUT AS #1 INPUT #1, x1, y1 INPUT #1, x2, y2 INPUT #1, x3, y3 CLOSE #1 l1 = SQR((x1 - x2) ^ 2 + (y1 - y2) ^ 2) l2 = SQR((x2 - x3) ^ 2 + (y2 - y3) ^ 2) l3 = SQR((x3 - x1) ^ 2 + (y3 - y1) ^ 2) p = (l1 + l2 + l3) / 2 s = SQR(p * (p - l1) * (p - l2) * (p - l3)) OPEN "OUTPUT.TXT" FOR OUTPUT AS #1 PRINT #1, s