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Problem
Problem
If
cos
2
θ
=
(
2
+
1
)
(
cos
θ
−
1
2
)
\cos 2\theta = (\sqrt{2} + 1)\left(\cos \theta - \frac{1}{\sqrt{2}}\right)
cos
2
θ
=
(
2
+
1
)
(
cos
θ
−
2
1
)
, then the value of
θ
\theta
θ
is a.
2
n
π
+
π
4
2n\pi + \frac{\pi}{4}
2
nπ
+
4
π
b.
2
n
π
±
π
4
2n\pi \pm \frac{\pi}{4}
2
nπ
±
4
π
c.
2
n
π
−
π
4
2n\pi - \frac{\pi}{4}
2
nπ
−
4
π
d. None of these
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