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Determinant of a triangular matrix equals
Asum of its diagonal entries
Bproduct of all its entries
Cproduct of its diagonal entries
Dalways zero
Answer & Solution
Correct answer: C. product of its diagonal entries
1. For an upper- or lower-triangular matrix, all entries above or below the diagonal vanish.
2. Cofactor expansion along the first column (or row) leaves a single diagonal product term.
3. Hence det = product of diagonal entries.
_Source: Maharashtra Balbharati Std XII Mathematics Part 1, Ch 2 "Matrices" §2.5_
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