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Byju's Answer
Standard XII
Mathematics
Trigonometric Ratios of Multiples of an Angle
Prove that : ...
Question
Prove that
:
cos
2
π
15
cos
4
π
15
cos
8
π
15
cos
16
π
15
=
1
16
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Solution
cos
2
π
15
.
cos
4
π
15
.
cos
8
π
15
.
cos
16
π
15
=
sin
2
4
.
2
π
15
16
.
sin
2
π
15
=
sin
3
π
15
16
sin
2
π
15
=
sin
(
2
π
+
2
π
15
)
16
sin
π
15
=
sin
2
π
/
15
16
sin
2
π
/
15
=
1
16
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2
Similar questions
Q.
Prove:
cos
2
π
15
cos
4
π
15
cos
8
π
15
cos
16
π
15
=
1
16
Q.
Cos2π/15cos4π/15cos8π/15cos16π/15=1/16
Q.
If
sin
x
≠
0
, prove that
cos
x
cos
2
x
cos
4
x
cos
8
x
=
sin
(
2
4
x
)
2
4
sin
x
and hence prove that
cos
2
π
15
cos
4
π
15
cos
8
π
15
cos
16
π
15
=
1
16
.
Q.
c
o
s
2
π
15
c
o
s
4
π
15
c
o
s
8
π
15
c
o
s
14
π
15
Q.
1.
cos
2
π
15
cos
4
π
15
cos
8
π
15
cos
16
π
15
=
1
16
.
2. One value of
A
which satisfies the equation
sin
4
A
−
2
sin
2
A
−
1
lies between 0 and
2
π
.
If 1,2 are true then enter 1 else 0.
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