1
AB/AC=2/3 = 2k/3k
BC²=AB²+BC²
(12√13)²=(2k)²+(3k)²
144*13=4k²+9k²
144=k²
k=12
AB=2*12=24
AC=3*12=36
Atriunghi= 24*36/2=432 cm²
2.
AB/AC=3/4=3k/4k
BC=√(3k)²+(4k)²=√25k²=5k
notam BD=x si DC=5k-x
AD²=(3k)²-x² =24²
AD²=(4k)²-(5k-x)²
(3k)²-x² =(4k)²-(5k-x)²
9k²-x²=16k²-25k²+10kx-x²
18k²=10kx
9k=5x= ⇒ k=5x/9
9*(5x/9)²-x² =576
25x²/9-x²=576
25x²-9x²=5184
16x²=5184
x²=324
x=18
k=5x/9=5*18/9=10
AB=3*10=30
AC=4*10=40
BC=5k=5*10=50
Perimetrul=P=30+40+50=120 cm
Atriunghi= 24x50/2=600 cm²