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Question-160618




Question Number 160618 by amin96 last updated on 03/Dec/21
Answered by mr W last updated on 03/Dec/21
Commented by mr W last updated on 03/Dec/21
a,b,c =radii  (a+b)^2 −(a−b)^2 =(2a)^2 −(2b)^2   ab=a^2 −b^2   ⇒b=((((√5)−1)a)/2)  (2a−c)^2 −c^2 =(a+b)^2 −(a−b)^2   ⇒c=a−b=(((3−(√5))a)/2)  A:B:C=a^2 :b^2 :c^2 =1:((3−(√5))/2):((7−3(√5))/2)                 ≈1:0.382:0.146
$${a},{b},{c}\:={radii} \\ $$$$\left({a}+{b}\right)^{\mathrm{2}} −\left({a}−{b}\right)^{\mathrm{2}} =\left(\mathrm{2}{a}\right)^{\mathrm{2}} −\left(\mathrm{2}{b}\right)^{\mathrm{2}} \\ $$$${ab}={a}^{\mathrm{2}} −{b}^{\mathrm{2}} \\ $$$$\Rightarrow{b}=\frac{\left(\sqrt{\mathrm{5}}−\mathrm{1}\right){a}}{\mathrm{2}} \\ $$$$\left(\mathrm{2}{a}−{c}\right)^{\mathrm{2}} −{c}^{\mathrm{2}} =\left({a}+{b}\right)^{\mathrm{2}} −\left({a}−{b}\right)^{\mathrm{2}} \\ $$$$\Rightarrow{c}={a}−{b}=\frac{\left(\mathrm{3}−\sqrt{\mathrm{5}}\right){a}}{\mathrm{2}} \\ $$$${A}:{B}:{C}={a}^{\mathrm{2}} :{b}^{\mathrm{2}} :{c}^{\mathrm{2}} =\mathrm{1}:\frac{\mathrm{3}−\sqrt{\mathrm{5}}}{\mathrm{2}}:\frac{\mathrm{7}−\mathrm{3}\sqrt{\mathrm{5}}}{\mathrm{2}} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\approx\mathrm{1}:\mathrm{0}.\mathrm{382}:\mathrm{0}.\mathrm{146} \\ $$
Commented by Tawa11 last updated on 03/Dec/21
Great sir
$$\mathrm{Great}\:\mathrm{sir} \\ $$

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