11) P=2×(l+L)=2×(250+475)=2×725=1450 m
a) P×5=1450×5=7250 m a parcurs sportivul
b) 7250m = 7,25 km
8- 7,25= 0,75 km mai are de alergat pt a parcurge 8 km
12) PΔABD+PΔABC= AC+CB+AB+AD+DB+AB=AC+CB+DB+AD+2AB=PABCD +2AB
24+36=40+2AB |-40
60-40=2AB
2AB=20
AB=20÷2
AB=10 cm
13) a) km; b) m; c) cm.