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Question-214220




Question Number 214220 by Ari last updated on 01/Dec/24
Answered by mr W last updated on 01/Dec/24
say a>b  a^2 +b^2 =c^2    ...(i)  a−b=6   ...(ii)  h_c =((ab)/c)=8   ...(iii)  (a−b)^2 =36  a^2 +b^2 −2ab=36  c^2 −16c−36=0  (c+2)(c−18)=0  ⇒c=18   ✓  ab=8×18=144  a, −b are roots of x^2 −6x−144=0  x=3±3(√(17))  ⇒a=3((√(17))+1), b=3((√(17))−1)
$${say}\:{a}>{b} \\ $$$${a}^{\mathrm{2}} +{b}^{\mathrm{2}} ={c}^{\mathrm{2}} \:\:\:…\left({i}\right) \\ $$$${a}−{b}=\mathrm{6}\:\:\:…\left({ii}\right) \\ $$$${h}_{{c}} =\frac{{ab}}{{c}}=\mathrm{8}\:\:\:…\left({iii}\right) \\ $$$$\left({a}−{b}\right)^{\mathrm{2}} =\mathrm{36} \\ $$$${a}^{\mathrm{2}} +{b}^{\mathrm{2}} −\mathrm{2}{ab}=\mathrm{36} \\ $$$${c}^{\mathrm{2}} −\mathrm{16}{c}−\mathrm{36}=\mathrm{0} \\ $$$$\left({c}+\mathrm{2}\right)\left({c}−\mathrm{18}\right)=\mathrm{0} \\ $$$$\Rightarrow{c}=\mathrm{18}\:\:\:\checkmark \\ $$$${ab}=\mathrm{8}×\mathrm{18}=\mathrm{144} \\ $$$${a},\:−{b}\:{are}\:{roots}\:{of}\:{x}^{\mathrm{2}} −\mathrm{6}{x}−\mathrm{144}=\mathrm{0} \\ $$$${x}=\mathrm{3}\pm\mathrm{3}\sqrt{\mathrm{17}} \\ $$$$\Rightarrow{a}=\mathrm{3}\left(\sqrt{\mathrm{17}}+\mathrm{1}\right),\:{b}=\mathrm{3}\left(\sqrt{\mathrm{17}}−\mathrm{1}\right) \\ $$
Commented by Ari last updated on 01/Dec/24
excuse me sir but why   h_c =((a.b)/c)?
$${excuse}\:{me}\:{sir}\:{but}\:{why}\: \\ $$$${h}_{{c}} =\frac{{a}.{b}}{{c}}? \\ $$
Commented by mr W last updated on 01/Dec/24
Commented by mr W last updated on 01/Dec/24
area of triangle =((ab)/2)  area of triangle =((ch_c )/2)  ⇒((ch_c )/2)=((ab)/2)  ⇒h_c =((ab)/c)
$${area}\:{of}\:{triangle}\:=\frac{{ab}}{\mathrm{2}} \\ $$$${area}\:{of}\:{triangle}\:=\frac{{ch}_{{c}} }{\mathrm{2}} \\ $$$$\Rightarrow\frac{{ch}_{{c}} }{\mathrm{2}}=\frac{{ab}}{\mathrm{2}} \\ $$$$\Rightarrow{h}_{{c}} =\frac{{ab}}{{c}} \\ $$
Commented by Ari last updated on 02/Dec/24
thank you Sir!
$${thank}\:{you}\:{Sir}! \\ $$

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