00:01
In this question, we need to prove that an orthogonal triangular matrix is always a diagonal matrix.
00:26
For that, let us consider an orthogonal triangular matrix a, which is given by a11, a12, a13, so on up to a1, n.
00:38
Then 0, then a22, a23, so on up to a2l, so on, we get 0 ,0 ,000, so on up to a &m.
00:53
This is a upper triangular orthogonal matrix.
00:57
Now if this matrix is orthogonal, then its product with its transport would be equal to identity matrix, that is a11, a12, a13, so on up to a1n, 0, a22, a23 so on up to a2n, 00, a33n, so on up to a3n, so on further 000 until an.
01:33
This is the matrix a, and then its transfer would be given by a11, a1, a12, a13, so on up to a1n, a1n.
01:44
A2, a2, a23, so on up to a2n, then 0 ,0, a33, so on up to a3n.
01:57
Further, go into 0 -0 -0, so on up to a -n -n.
02:03
It is equal to identity 1 -0 -0 -0 -0 -0 -0 -0 -0 -0 -0 -0 -0 -0 -0 -0 -0 -1, so on up to 0 -0 -0 -0 -0 -0 -0 -0 -0 -0 -1.
02:18
Now, multiplying the first row with its matrix, we get a11 plus a12 square plus a13 square 1 up to a1 and square is equal to 0, is equal to 1...