A= d1 ×d2 / 2
Notam rombul ABCD, cu diagonalele AC, BD, intersectia diagonalelor este O.
BD = 48
BO = BD/2= 24
In Δ BOC (dreptunghic in O, BC-ipotenuza, BO si CO catete):
BC²= BO² +CO²
CO²= BC²-BO²
CO²= 676-576
CO²= 100
⇒CO = 10
AC = 2 ×CO = 20
A= d1 ×d2 /2 = BD ×AC / 2 = 48 × 20/2 = 480 cm²