Question

the orthogonal matrix of [1 2 3,2 1 3, 3 3 1]​

Answer 1

a = –2, b = –1

Explanation:

AAT = I ⇒ a + 4 + 2b = 0, 2a + 2 – 2b = 0 & a2 + 4 + b2 = 9 gives a = –2, b = –1.

If A = 1/3[(1,2,2)(2,1,-2),(a,2,b)] is an orthogonal matrix, then (a) a = 2, b = 1 (b) a = –2, b = –1 (c) a = 2, b = –1 (d) a = –2, b = 1