a)
P = 25 cm²
a = √25 = 5
O = 4a = 4*5
Obw = 20 cm
Obwód wynosi 20cm.
b)
P = 24cm²
h = 4cm
P = ah
24 = a4 |:4
a = 6cm
O = 4a
Obw = 4*6 = 24 cm
Obwód wynosi 24 cm.
c)
P = 20cm²
P = (a+b)*h : 2
a=6cm
b = 4cm
20 = (6+4) * h :2
20 = 10h : 2
20 = 5h |:5
h = 4
wysokość wynosi 4 cm.