Răspuns:

11. P=2×(4 dm + 32 cm)=2×(40 cm + 32 cm)=2×72 cm=144 cm

18.

a) ABC = ADC = 40°

DAB = DCB = 180° - 40° = 140°

b) ABC = ADC = 50°

DAB = DCB = 180° - 50° = 130°

c) ABC = ADC = 100°

DAB = DCB = 180° - 100° = 80°

d) ABC = ADC = 70° 30'

DAB = DCB = 180° - 70° 30' = 109° 30'

21.

A+B+C=230°

D=360°-230°

=130°

B=D=130°

A=C=180°-130°=50°