a) Pp= 6 cm • 8 cm •1/2 = 48 cm2 • 1/2= 24 cm2
Pb= 8 cm • 7 cm + 6 cm• 7 cm + 10 cm• 7 cm = 168 cm2
Pc= 2•24 cm2 + 168 cm2 = 48 cm2 + 168 cm2 = 216 cm2
b) Pp = ((6 cm +12 cm )•4 cm)•0,5=(18 cm • 4 cm)•0,5= 72 cm2• 0,5= 36 cm2
Pb=2•(13 cm • 5 cm) + 6 cm • 13 cm + 12 cm •13 cm = 130 cm2 + 78 cm2 + 156 cm2 = 364 cm2
Pc= 364 cm2 + 36 cm2 = 400 cm2