n
2
3
4
5
6
7
8
9
1
0
s
i
n
(
2
θ
)
=
2
s
i
n
(
θ
)
c
o
s
(
θ
)
c
o
s
(
2
θ
)
=
2
c
o
s
(
θ
)
-
2
s
i
n
(
θ
)