r
a
d
i
u
s
o
f
B
1
r
a
d
i
u
s
o
f
B
2
r
a
d
i
u
s
o
f
B
3
B
1
⋂
B
2
≠
∅
F
a
l
s
e
x
∈
B
1
F
a
l
s
e
x
∈
B
2
F
a
l
s
e
B
3
⊂
B
1
⋂
B
2
F
a
l
s
e
x
∈
B
3
F
a
l
s
e