r
θ
z
s
i
n
g
l
e
r
s
i
n
g
l
e
θ
s
i
n
g
l
e
z
0
≤
r
≤
1
,
0
≤
θ
≤
7
π
4
,
0
≤
z
≤
2
(
s
o
l
i
d
)