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If
A
=
[
1
sin
θ
1
−
sin
θ
1
sin
θ
−
1
−
sin
θ
1
]
A = \begin{bmatrix} 1 & \sin\theta & 1 \\ -\sin\theta & 1 & \sin\theta \\ -1 & -\sin\theta & 1 \end{bmatrix}
A
=
1
−
sin
θ
−
1
sin
θ
1
−
sin
θ
1
sin
θ
1
…
Mathematics
Problem
If
A
=
[
1
sin
θ
1
−
sin
θ
1
sin
θ
−
1
−
sin
θ
1
]
A = \begin{bmatrix} 1 & \sin\theta & 1 \\ -\sin\theta & 1 & \sin\theta \\ -1 & -\sin\theta & 1 \end{bmatrix}
A
=
1
−
sin
θ
−
1
sin
θ
1
−
sin
θ
1
sin
θ
1
; then for all
θ
∈
(
3
π
4
,
5
π
4
)
\theta \in \left(\frac{3\pi}{4}, \frac{5\pi}{4}\right)
θ
∈
(
4
3
π
,
4
5
π
)
,
det
(
A
)
\det(A)
det
(
A
)
lies in the interval : (1)
[
5
2
,
4
)
\left[\frac{5}{2}, 4\right)
[
2
5
,
4
)
(2)
[
3
2
,
3
]
\left[\frac{3}{2}, 3\right]
[
2
3
,
3
]
(3)
(
0
,
3
2
]
\left(0, \frac{3}{2}\right]
(
0
,
2
3
]
(4)
(
1
,
5
2
]
\left(1, \frac{5}{2}\right]
(
1
,
2
5
]
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