a) [AC]U(BC =[AC
b) [BA U [BD = AD (dreapta)
c) [CA U [BA = [CA
d) [DB U [CA = [DA
e) [AB ∩ [CD = [CD
f) [BC ∩ (CD = [BD
g) (AB ∩ (CA = (AC)
h) [BD ∩ [CA = [BC]
i) [AB-(CD = [AC]
j) [CA-[DB = ∅
k) [DA-(BC = [BA
l) (BA-(CD = (BA
m) [AB] U (BC] = [AC]
n) [AB U [BD) = [AD)
o) [AC] U (BD) = [AD)
p) [BC] U [CD] = [BD]
q)[AC ∩[BD] = [BD]
r)[AD] ∩ [BC] = [BC]
s)[AD] ∩ [CD] = [CD]
s)[BD] ∩ [AD] = [BD]
t)[AB] ∩ [BD] = {B} (punctul B)
t)[AC] ∩ (CD) = ∅
u)[AC]-[BC] = [AB)
v)[BD] - (CD) = [BC]
w)(AD)-(BD) = (AB]
