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Mathematics
Mathematics
Problem
Which of the following lists all the solutions of
cos
(
3
θ
)
=
cos
θ
\cos(3\theta)=\cos\theta
cos
(
3
θ
)
=
cos
θ
in the interval
0
≤
θ
<
2
π
0\le \theta < 2\pi
0
≤
θ
<
2
π
? a)
{
0
,
π
}
\{0,\;\pi\}
{
0
,
π
}
b)
{
π
2
,
π
,
3
π
2
}
\left\{\dfrac{\pi}{2},\;\pi,\;\dfrac{3\pi}{2}\right\}
{
2
π
,
π
,
2
3
π
}
c)
{
0
,
π
2
,
π
,
3
π
2
}
\{0,\;\dfrac{\pi}{2},\;\pi,\;\dfrac{3\pi}{2}\}
{
0
,
2
π
,
π
,
2
3
π
}
d)
{
π
3
,
π
,
5
π
3
}
\left\{\dfrac{\pi}{3},\;\pi,\;\dfrac{5\pi}{3}\right\}
{
3
π
,
π
,
3
5
π
}
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