a
p
e
x
a
n
g
l
e
φ
π
3
π
2
2
π
3
5
π
6
n
u
m
b
e
r
o
f
c
e
l
l
s
1
3
5
7
a
r
m
v
e
c
t
o
r
s
ℓ
1
2
ℓ
2
2
W
v
e
c
t
o
r
(
w
1
,
w
2
)
w
1
1
w
2
1
