1.

Let `A = [(1,sin theta,1),(- sin theta,1,sin theta),(-1,-sin theta,1)], " where " 0 le theta lt 2 pi`. then, which of the following is not correct ?A. `D = 0`B. `D in (0, oo)`C. `D in [2, 4]`D. `D in [2, oo)`

Answer» Correct Answer - C
We have,
`D = |(1,sin theta,1),(- sin theta,1,sin theta),(-1,- sin theta,1)|`
`rArr D = |(2,sin theta,1),(0,1,sin theta),(0,- sin theta,1)| " " ["Applying " C_(1) rarr C_(1) + C_(3)]`
`rArr D = 2 (1 + sin^(2) theta)`
Now, `0 le sin^(2) theta le 1`
`rArr 2 le 2 (1 + sin^(2) theta) le 4 rArr D in [2, 4]`


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