1. Masura unghiurilor intr-un patrulater=360.
Toate unghiurile egale => masura unui unghi=360:4=90.
2.a+b+c+d=360
a=(b+c+d)/3 sau 3a=b+c+d (I)
b=(c+d)/2 sau 2b=c+d (II)
c=d/2 sau 2c=d
(I),(II) => 3a=3b sau a=b
Inlocuim in ecuatia de baza si avem b+b+c+2c=360 sau 2b+3c=360
Dar 2b=c+d=3c
=>3c+3c=360 =>c=60 =>d=120
a=b=(360-120-60)/2
a=b=90
3.a+b+c=180
a/3=b/2=c/4=k
a=3k
b=2k
c=4k
3k+2k+4k=180
9k=180 =>k=20
=>a=60
=>b=40
=>c=80
MC_l_CB(ip.)=>m(∡MCB)=90° la fel si m(∡CMA)=90°(AM║BC-ip.)
=>m(∡BAM)=360-90-90-40=140°