Построить два отрезка - QBasic (244491)

DECLARE FUNCTION P3! (x1!, y1!, x2!, y2!, x3!, y3!)
CLS
RANDOMIZE TIMER
CONST eps = .000001
 
x1 = 20 * RND - 10
y1 = 20 * RND - 10
x2 = 20 * RND - 10
y2 = 20 * RND - 10
x3 = 20 * RND - 10
y3 = 20 * RND - 10
x4 = 20 * RND - 10
y4 = 20 * RND - 10
 
s1 = P3(x1, y1, x3, y3, x4, y4)
s2 = P3(x2, y2, x3, y3, x4, y4)
s3 = P3(x3, y3, x1, y1, x2, y2)
s4 = P3(x4, y4, x1, y1, x2, y2)
 
IF ABS(s1 + s2 - s3 - s4) < eps THEN k = -1
 
IF k THEN PRINT "YES" ELSE PRINT "NO"
 
FUNCTION P3 (x1, y1, x2, y2, x3, y3)
   P3 = ABS((x2 - x1) * (y3 - y1) - (x3 - x1) * (y2 - y1))
END FUNCTION