Null matrix upper triangular matrix and lower triangular matrix

In a square matrix A=[a_(ij)] if igtj and a_(ij)=0 then matrix is called Square matrix Lower triangular matrix Upper triangular matrix Unit matrix

Let R be a square matrix of order greater than 1 such that R is upper triangular matrix .Further suppose that none of the diagonal elements of the square matrix R vanishes. Then (A) R must be non singular (B) R^-1 does not exist (C) R^-1 is an upper triangular matrix (D) R^-1 is a lower triangular matrix

Let R be a square matrix of order greater than 1 such that R is lower triangular.Further suppose that none of the diagonal elements of the square matrix R vanishes. Then (A) R must be non singular (B) R^-1 does not exist (C) R^-1 is an upper triangular matrix (D) R^-1 is a lower triangular matrix

Which of the following is a triangular matrix? (A) a scalar matrix (B) a lower triangular matrix (C) an upper triangular matrix (D) a diagonal matrix

Which of the following is a triangular matrix? (A) a scalar matrix (B) a lower triangular matrix (C) an upper triangular matrix (D) a diagonal matrix

Define triangular Matrix.