Odpowiedź :
obw = a + b + c
p = a*h:2 albo p=[tex]\frac{a+b+c}{2}[/tex] ( wzór herona )
a = 3cm
b = 4cm
c = 5cm
obw = 3 + 4 + 5 = 12cm
p = [tex]\frac{3+4+5}{2}[/tex]=6cm²
[tex]a = 3 \ cm\\b = 0,4 \ dm = 4 \ cm\\c = 50 \ mm =5 \ cm\\\\P = \frac{1}{2}ah\\\\h = b\\\\P = \frac{1}{2}ab = \frac{1}{2}\cdot 3 \ cm\cdot4 \ cm = 6 \ cm^{2}\\\\Obw = a+b+c = 3 \ cm + 4 \ cm + 5 \ cm = 12 \ cm[/tex]