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Consider the matrix Aα = [cosα-sinαsinαcosα] Find all possible real values of α satisfying the condition AATAα+AαT = I - Mathematics

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प्रश्न

Consider the matrix Aα = `[(cos alpha, - sin alpha),(sin alpha, cos alpha)]` Find all possible real values of α satisfying the condition `"A"_alpha + "A"_alpha^"T"` = I

बेरीज

उत्तर

Aα = `[(cos alpha, - sin alpha),(sin alpha, cos alpha)]`

`"A"_alpha^"T" = [(cos alpha, sin alpha),(-sin alpha, cos alpha)]`

`"A"_alpha + "A"_alpha^"T" = [(cos alpha, - sin alpha),(sin alpha, cos alpha)] + [(cos alpha, sin alpha),(-sin alpha, cos alpha)]`

= `[(cos alpha + cos alpha, -sinalpha + sin alpha),(sin alpha - sin alpha, cos alpha + cos alpha)]`

`"A"_alpha + "A"_alpha^"T" = [(2cos alpha, 0),(0, 2 cos alpha)]`

Given `"A"_alpha + "A"_alpha^"T"` = I

∴ `[(2cos alpha, 0),(0, 2 cos alpha)] = [(1, 0),(0, 1)]`

`2 cos  alpha` = 1

⇒ `cos allpha = 1/2`

The general solution is α = `2"n"  pi +-  pi/3, "n" ∈ "Z"`

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  या प्रश्नात किंवा उत्तरात काही त्रुटी आहे का?
पाठ 7: Matrices and Determinants - Exercise 7.1 [पृष्ठ १८]

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सामाचीर कलवी Mathematics - Volume 1 and 2 [English] Class 11 TN Board
पाठ 7 Matrices and Determinants
Exercise 7.1 | Q 6. (ii) | पृष्ठ १८

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