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A rectangle \mathrm{R} with end points of one of its sides as (1,2)$ and $(3,6) is inscribed in a circle. If the equation of a diameter of the circle is  2 x-y+4=0, then the area of \mathrm{R} is______________.

Option: 1

16


Option: 2

-


Option: 3

-


Option: 4

-


Answers (1)

best_answer

Let the cetre of the circle is  C(\alpha, 4+2 \alpha)

It will be equidistant from \mathrm{(1,2)(3,6)}

\mathrm{\Rightarrow(\alpha-1)^{2}+(4+2 \alpha-2)^{2}=(\alpha-3)^{2}+(4+2 \alpha-6)^{2}} \\

\mathrm{\Rightarrow \alpha^{2}-2 \alpha+1+4 \alpha^{2}+8 \alpha+4=\alpha^{2}-6 \alpha+3+4 \alpha^{2}-8 \alpha+4 }\\

\mathrm{\Rightarrow 20 \alpha=8 \Rightarrow \alpha=\frac{4}{5} ; \quad c:\left(\frac{4}{5}, \frac{28}{5}\right) .}

\mathrm{\text { distance b/w }(1,2) \quad \&(3,6)=2 \sqrt{5}=l e n g t h \text {. }}

\mathrm{Equation\: of\: line\: joining (1,2) and(3,6) is} \\

\mathrm{y-2=\frac{6-2}{3-1}(x-1)}

\mathrm{2x-y= 0}

\mathrm{distance\: of \: centre\: from \: 2 x-y=0\: is}\\

\mathrm{d=\frac{\left|2 \times \frac{4}{5}-\frac{28}{5}\right|}{\sqrt{2^{2}+1^{2}}}=\frac{4}{\sqrt{5}} \text { units } }

\mathrm{So\: Breadth\: \: 2 \times \frac{4}{\sqrt{5}}=\frac{8}{\sqrt{5}} units}\\

\mathrm{Area \: of \: R=l \times b=2 \sqrt{5} \times \frac{8}{\sqrt{5}}=16 \mathrm{sq} .u n i t s.}

So answer is \mathrm{16 \mathrm{sq} .u n i t s.}

Posted by

Ritika Kankaria

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