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Tardigrade
Question
Mathematics
The value of cos 0+ cos (π/9)+ cos (2 π/9)+ cos (3 π/9)+ cos (4 π/9)+ cos (5 π/9)+ cos (6 π/9)+ cos (7 π/9)+ cos (8 π/9) is
Q. The value of
cos
0
+
cos
9
π
+
cos
9
2
π
+
cos
9
3
π
+
cos
9
4
π
+
cos
9
5
π
+
cos
9
6
π
+
cos
9
7
π
+
cos
9
8
π
is
171
172
Trigonometric Functions
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A
2
1
8%
B
−
2
1
23%
C
0
15%
D
1
54%
Solution:
1
+
cos
9
π
+
cos
9
2
π
+
cos
9
3
π
+
cos
9
4
π
−
cos
9
4
π
−
cos
9
3
π
−
cos
9
2
π
−
cos
9
π
=
1