Triangular matrix : A matrix is said to be a triangular matrix if, either 1.every element above principal diagonal is zero. 2.1.every element below principal diagonal is zero.  upper triangular matrix : A matrix is said to be upper triangular if, every element below principal diagonal is zero. Lower triangular matrix : matrix is said to be a triangular matrix if, every element above principal diagonal is zero. Note ( both of eg. listed above) transpose of matrix : if A is a matrix of type m×n obtained by interchanging it's rows and column is called tranpose of A and is denoted by A' or A^T.
Matrices chapter 1 Matrix :A set of m×n number arranged in the form of ordered set of m rows, each row consisting of n numbers and enclosed in the bracket [] is called m×n type of matrix. for eg. a11 a12.. .. . .. .. .a1n a21 a22. ... .. .. ..a2n ..... .. ... .. .. .. . .. ... ... am1 am2 .. . .. amn m×n Rectangular Matrix : m×n matrix is said to be rectangular matrix if m not equal to n. for eg. 1 2 ...