Question Number 19783 by NECC last updated on 15/Aug/17
$${The}\:{sides}\:{of}\:{a}\:{triangle}\:{are}\:{of} \\ $$$${lengths}\:\sqrt{\left({m}^{\mathrm{2}} −{n}^{\mathrm{2}} \right)}\:,{m}^{\mathrm{2}} +{n}^{\mathrm{2}} ,\:\mathrm{2}{mn}. \\ $$$${Show}\:{that}\:{it}\:{is}\:{a}\:{right}\:{angle}\:\Delta. \\ $$
Commented by Tinkutara last updated on 15/Aug/17
$$\mathrm{Right}\:\mathrm{triangle}\:\mathrm{is}\:\mathrm{not}\:\mathrm{possible}\:\mathrm{with}\:\mathrm{these} \\ $$$$\mathrm{sides}. \\ $$
Commented by NECC last updated on 15/Aug/17
$${please}\:{prove}\:{your}\:{statement} \\ $$$${mathematically}. \\ $$
Commented by Tinkutara last updated on 15/Aug/17
$$\mathrm{Since}\:{m}^{\mathrm{2}} \:−\:{n}^{\mathrm{2}} \:+\:\mathrm{4}{m}^{\mathrm{2}} {n}^{\mathrm{2}} \:\neq\:{m}^{\mathrm{4}} \:+\:{n}^{\mathrm{4}} \:+ \\ $$$$\mathrm{2}{m}^{\mathrm{4}} {n}^{\mathrm{4}} .\:\mathrm{Hence}\:\mathrm{right}\:\mathrm{triangle}\:\mathrm{is}\:\mathrm{not} \\ $$$$\mathrm{possible}. \\ $$
Answered by Rasheed.Sindhi last updated on 15/Aug/17
$$\left(\mathrm{m}^{\mathrm{2}} −\mathrm{n}^{\mathrm{2}} \right)^{\mathrm{2}} +\left(\mathrm{2mn}\right)^{\mathrm{2}} \\ $$$$=\mathrm{m}^{\mathrm{4}} −\mathrm{2m}^{\mathrm{2}} \mathrm{n}^{\mathrm{2}} +\mathrm{n}^{\mathrm{4}} +\mathrm{4m}^{\mathrm{2}} \mathrm{n}^{\mathrm{2}} \\ $$$$=\mathrm{m}^{\mathrm{4}} +\mathrm{2m}^{\mathrm{2}} \mathrm{n}^{\mathrm{2}} +\mathrm{n}^{\mathrm{4}} \\ $$$$=\left(\mathrm{m}^{\mathrm{2}} +\mathrm{n}^{\mathrm{2}} \right)^{\mathrm{2}} \\ $$$$\mathrm{Hence}\:\mathrm{rightangle}\:\mathrm{triangle}. \\ $$
Commented by Tinkutara last updated on 15/Aug/17
$$\mathrm{But}\:\mathrm{the}\:\mathrm{side}\:\mathrm{is}\:\sqrt{{m}^{\mathrm{2}} \:−\:{n}^{\mathrm{2}} }.\:\mathrm{Its}\:\mathrm{square} \\ $$$$\mathrm{will}\:\mathrm{be}\:{m}^{\mathrm{2}} \:−\:{n}^{\mathrm{2}} \:\mathrm{only}.\:\left(\mathrm{OK},\:\mathrm{it}\:\mathrm{can}\:\mathrm{be}\right. \\ $$$$\mathrm{considered}\:\mathrm{a}\:\mathrm{typing}\:\mathrm{error}\:\mathrm{in}\:\mathrm{the} \\ $$$$\left.\mathrm{question}\right) \\ $$
Commented by NECC last updated on 16/Aug/17
$${thanks}….\:{its}\:{clear}\:{now}. \\ $$