A=(-1;-2), B=(3,4), C=(2;-3)
|AB| = √(3+1)² + (4 +2)² = √4²+√6² = √16+ 36 = √52 = 2√13
|BC| = √(2-3)² + (-3 - 4)² = √-1² + (-7)² = √1+49 = √50 = 5√2
|AC| = √(2 +1)² + (-3 +2)² = √3² + (-1)² = √9 + 1 = √10
Obw ABC = 2√13 + 5√2 + √10
P = 1/2 * √10 * 5√2
