A(xA, yA); B(xb, yB)
AB=√[(xB-xA)²+(yB-yA)²)]
A(1,6),B(-3,2),C(1,-2)si D(5,2)
AB=√[(-3-1)²+(2-6)²)]= √32=4√2
BC=√[(1+3)²+(-2-2)²)]= √32=4√2
CD==√[(5-1)²+(2+2)²)]= √32=4√2
AD=√[(5-1)²+(2-6)²)]= √32=4√2
toate laturile sunt egale => ABCD romb sau patrat
latura =4√2 (u. l)
AC=√[(1-1)²+(-2-6)²)]= √64=8
BD=√[(5+3)²+(2-2)²)]= √64=8
Diagonalele sunt egale => ABCD e patrat
Aria ABCD=latura²=(4√2) ²=32 (u.a)
