Proving $\sqrt{2}+\sqrt{3} \gt \pi$: A Mathematical Challenge

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SUMMARY

The mathematical challenge of proving that $\sqrt{2}+\sqrt{3} > \pi$ has been discussed, with particular focus on the inequality involving absolute values. The argument presented by Albert emphasizes the relationship between the values of $\sqrt{3}$, $\pi/2$, and $\sqrt{2}$. The key inequality discussed is $\Bigl|\sqrt{3}-\dfrac{\pi}{2}\Bigr| > \Bigl|\dfrac{\pi}{2}-\sqrt{2}\Bigr|$, which is central to the proof. Understanding this inequality is crucial for grasping the overall proof structure.

PREREQUISITES
  • Understanding of absolute value inequalities
  • Familiarity with basic properties of square roots
  • Knowledge of the mathematical constant $\pi$
  • Basic algebraic manipulation skills
NEXT STEPS
  • Study absolute value inequalities in depth
  • Explore properties of irrational numbers, specifically $\sqrt{2}$ and $\sqrt{3}$
  • Investigate the significance of $\pi$ in mathematical proofs
  • Learn about mathematical proof techniques, including direct and indirect proofs
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Mathematics students, educators, and enthusiasts interested in inequalities and proof techniques will benefit from this discussion.

anemone
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Prove $\sqrt{2}+\sqrt{3}\gt \pi$.
 
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anemone said:
Prove $\sqrt{2}+\sqrt{3}\gt \pi$.
$\begin{vmatrix}
\sqrt 3-\dfrac{\pi}{2}
\end{vmatrix}>\begin{vmatrix}
\sqrt 2-\dfrac{\pi}{2}
\end{vmatrix}=\begin{vmatrix}
\dfrac{\pi}{2}-\sqrt 2
\end{vmatrix}$
we have:
$\sqrt 3-\dfrac{\pi}{2}>\dfrac {\pi}{2}-\sqrt 2>0$
$\therefore \sqrt 3+\sqrt 2>\pi$
the proof is done
 
Albert said:
$\begin{vmatrix}
\sqrt 3-\dfrac{\pi}{2}
\end{vmatrix}>\begin{vmatrix}
\sqrt 2-\dfrac{\pi}{2}
\end{vmatrix}=\begin{vmatrix}
\dfrac{\pi}{2}-\sqrt 2
\end{vmatrix}$
we have:
$\sqrt 3-\dfrac{\pi}{2}>\dfrac {\pi}{2}-\sqrt 2>0$
$\therefore \sqrt 3+\sqrt 2>\pi$
the proof is done

Very well done, Albert!(Clapping)
 
Albert said:
$\begin{vmatrix}
\sqrt 3-\dfrac{\pi}{2}
\end{vmatrix}>\begin{vmatrix}
\sqrt 2-\dfrac{\pi}{2}
\end{vmatrix}=\begin{vmatrix}
\dfrac{\pi}{2}-\sqrt 2
\end{vmatrix}$
we have:
$\sqrt 3-\dfrac{\pi}{2}>\dfrac {\pi}{2}-\sqrt 2>0$
$\therefore \sqrt 3+\sqrt 2>\pi$
the proof is done
[sp]I don't understand this argument. Why is $\Bigl|\sqrt 3-\dfrac{\pi}{2}\Bigr| > \Bigl|\dfrac{\pi}{2}-\sqrt 2\Bigr|$?[/sp]
 
Opalg said:
[sp]I don't understand this argument. Why is $\Bigl|\sqrt 3-\dfrac{\pi}{2}\Bigr| > \Bigl|\dfrac{\pi}{2}-\sqrt 2\Bigr|$?[/sp]

if $\Bigl|A\Bigr| > \Bigl|B\Bigr|$
and $\Bigl|B\Bigr| = \Bigl|C\Bigr|$
then
$\Bigl|A\Bigr| > \Bigl|C\Bigr|$
 
Last edited by a moderator:
Opalg said:
[sp]I don't understand this argument. Why is $\Bigl|\sqrt 3-\dfrac{\pi}{2}\Bigr| > \Bigl|\dfrac{\pi}{2}-\sqrt 2\Bigr|$?[/sp]

Albert said:
if $\Bigl|A\Bigr| > \Bigl|B\Bigr|$
and $\Bigl|B\Bigr| = \Bigl|C\Bigr|$
then
$\Bigl|A\Bigr| > \Bigl|C\Bigr|$

I have long thought about the validity of Albert's solution, but his argument I think is also built on the facts that he knows $\sqrt{3}>\dfrac{\pi}{2}$ and also, $\sqrt{2}<\dfrac{\pi}{2}$.

Anyway, here is my solution:

We could use the well-known inequality that says $\dfrac{22}{7}>\pi$ to assist in my method of proving, as shown below:

Note that

$7938>7921$

$2(63)^2>89^2$

$\sqrt{2}>\dfrac{89}{63}$ and

$762048>760384$

$3(504)^2>872^2$

$\sqrt{3}>\dfrac{872}{504}$,

$\therefore \sqrt{2}+\sqrt{3}>\dfrac{22}{7}>\pi$ and we're hence done.
 
it is very easy to prove $\sqrt 3>\dfrac {\pi}{2}$ , and $\sqrt 2<\dfrac {\pi}{2}$
for :
$2<2.25=\dfrac{3^2}{4}<(\dfrac {\pi}{2})^2<\dfrac {3.2^2}{4}=2.56<3$
 
Last edited by a moderator:

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