laturile a ,b ,c
a / 2 = b /3 = c / 5 = ( a +b+c ) / ( 2 + 3 +5 ) = 20 / 10 = 2 cm
suma = 80cm = 4a +4b+4c
4(a + b+ c ) = 80
a +b +c = 20
a /2 =2 a = 4 cm
b /3 =2 b = 6 cm
c / 5 =2 c = 10 cm
d² = a² + b² +c² = 4² +6² +10² = 16 + 36 + 100 = 152cm²
d= √152 = 2√38 cm