Problema 21, vă rog!

Răspuns:
AB/BC=3/4
AC=10cm diagonala
AC²=AB²+BC²=(3BC/4)²+¹⁶BC²
AC²=(9BC²+16BC²)/16=25BC²/16
16×100/25=BC²
BC=40/5=8cm
AB=3BC/4=3×8/4=6cm
Perimetru=8×2+6×2=16+12=28cm