1). L = 6 cm
l = 4 cm
P = 2×( L + l ) = 2 × ( 6 + 4 ) = 2 × 10 = 20 cm
2). L = 8 cm
l = 8 : 4 = 2 cm
P = 2 × ( 8 + 2 ) = 2 × 10 = 20 cm
3). L |.....|.....|.....| -> 149
l. |.....|-7|
P = 298 cm
Semiperimetrul = 298 : 2 = 149 cm
149 + 7 = 156
156 : 4 = 39 ( are un segment )
latimea = 39 - 7 = 32 cm
lungimea = 39 × 3 = 117 cm