По координатам трёх вершин некоторого треугольника найдите площадь и периметр

CLS
INPUT "x (1 vershini)"; x1
INPUT "y (1 vershini)"; y1
INPUT "x (2 vershini)"; x2
INPUT "y (2 vershini)"; y2
INPUT "x (3 vershini)"; x3
INPUT "y (3 vershini)"; y3
a = SQR((x2 - x1) ^ 2 + (y2 - y1) ^ 2)
b = SQR((x3 - x2) ^ 2 + (y3 - y2) ^ 2)
c = SQR((x1 - x3) ^ 2 + (y1 - y3) ^ 2)
p = (a + b + c) / 2
s = SQR(p * (p - a) * (p - b) * (p - c))
PRINT "S:"; s
PRINT "P:"; p * 2

CLS
INPUT "n"; n
DIM c(n)
PRINT "zapolnenie massiva C"
FOR i = 1 TO n
    INPUT c(i)
NEXT
CLS
PRINT "massiv:"
FOR i = 1 TO n
    PRINT c(i);
NEXT
PRINT
PRINT " znachenie Z:"
b = 5
FOR i = 1 TO n
    PRINT (a + b + c(i)) / i;
    c = c + 1
    b = b + 1
NEXT

CLS
INPUT "n"; n
DIM a(n, n)
FOR i = 1 TO n: FOR j = 1 TO n
        INPUT a(i, j)
NEXT: NEXT
CLS
PRINT "tablica:"
FOR i = 1 TO n: FOR j = 1 TO n
        PRINT a(i, j);
NEXT: PRINT: NEXT
FOR i = 2 TO n - 1: FOR j = 2 TO n - 1
        IF a(i, j) = 1 AND a(i - 1, j) = 1 AND a(i, j - 1) = 1 AND a(i, j + 1) = 1 AND a(i + 1, j) = 1 THEN k = k + 1
NEXT: NEXT
PRINT "kol-vo"; k