Let for some real numbers $\alpha$ and $\beta$, $a = \alpha - i\beta$. If the system of equations $4ix + (1 + i)y = 0$ and $$8\left( {\cos {{2\pi } \over 3} + i\sin {{2\pi } \over 3}} \right)x + \overline a y = 0$$ has more than one solution, then ${\alpha \over \beta }$ is equal to
Solution
<p>Given $a = \alpha - i\beta$ and</p>
<p>$4ix + (1 + i)y = 0$ ...... (i)</p>
<p>$$8\left( {\cos {{2\pi } \over 3} + i\sin {{2\pi } \over 3}} \right)x + \overline a y = 0$$ .... (ii)</p>
<p>By (i)</p>
<p>${x \over y} = {{ - (1 + i)} \over {4i}}$ ...... (iii)</p>
<p>By (ii)</p>
<p>$${x \over y} = {{ - \overline a } \over {8\left( {{{ - 1} \over 2} + {{\sqrt 3 i} \over 2}} \right)}}$$ ..... (iv)</p>
<p>Now by (iii) and (iv)</p>
<p>$${{1 + i} \over {4i}} = {{\overline a } \over {4\left( { - 1 + \sqrt 3 i} \right)}}$$</p>
<p>$$ \Rightarrow \overline a = \left( {\sqrt 3 - 1} \right) + \left( {\sqrt 3 + 1} \right)i$$</p>
<p>$$ \Rightarrow \alpha + i\beta = \left( {\sqrt 3 - 1} \right) + \left( {\sqrt 3 + 1} \right)i$$</p>
<p>$\therefore$ ${\alpha \over \beta } = {{\sqrt 3 - 1} \over {\sqrt 3 + 1}} = 2 - \sqrt 3$</p>
About this question
Subject: Mathematics · Chapter: Trigonometric Functions · Topic: Trigonometric Ratios and Identities
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