Parallel Mirage


$ AFG $ একটি ত্রিভুজ.  $AF$ এবং $AG$ এর উপর $B$ এবং $C$ এমন দুইটি বিন্দু যেন $FB=BC=CG$। $\angle ABC$ এবং $\angle ACB$ কোণের সমদ্বিখন্ডক $AG$ এবং $AF$ বাহুকে যথাক্রমে $E$ এবং $D$ বিন্দুতে ছেদ করে. প্রমাণ কর যে, $DE\mid\mid FG$।


Proof Based Problems  


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Solution

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$BF=BC \implies \angle BCF = \angle BFC$

$Also, $\angle BCF = 180 - \angle BFC - \angle FBC $

$\implies BCF = \frac{180-\angle FBC}{2} = \frac{\angle ABC}{2} = \angle EBC$

So, $BE\mid\mid CF$

In the same way, $BG\mid\mid CD$

\[BE\mid\mid CF \implies \frac{AB}{AF} =\frac{AE}{AC}\]

\[BG\mid\mid CD \implies \frac{AB}{AD} =\frac{AG}{AC}\]

Dividing the equations

\[\frac{AF}{AD} = \frac{AG}{AE}\]

So, $GF\mid\mid DE$

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