3)
a+b+c+d=360
{a,b,c,d}={2,5,;2;1,5;3}
a/2,5=k⇒a=2,5k
b/2=k ⇒b=2k
c/1,5=k ⇒c=1,5k
d/3=k ⇒ d=3k
2,5k+2k+1,5k+3k=360
9k=360
k=360/9
k=40
a=2,5k=2,5x40=100
a=100
b=2k=2x40=80
b=80
c=1,5k=1,5x40=60
c=60
d=3k=3x40=120
d=120
100+80+60+120=360
4) unghiurile opuse la un patrulater sunt congruente
unghiurile alaturate sunt suplementare
1b) suma unghiurilor unui patrulater convex este de 360 grade