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Mathematics
Problem
csc
−
1
(
cos
x
)
\csc^{-1}(\cos x)
csc
−
1
(
cos
x
)
is real if (a)
x
∈
[
−
1
,
1
]
x \in [-1, 1]
x
∈
[
−
1
,
1
]
(b)
x
∈
R
x \in R
x
∈
R
(c)
x
x
x
is an odd multiple of
π
2
\frac{\pi}{2}
2
π
(d)
x
x
x
is a multiple of
π
\pi
π
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