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Vojtěch Jarník IMC
1998 VJIMC
Problem 4-M
sum of sqrt(1-k^2/n^2) inequality
sum of sqrt(1-k^2/n^2) inequality
Source: VJIMC 1998 1.4-M
August 2, 2021
inequalities
integration
calculus
Riemann sum
Problem Statement
Prove the inequality
n
π
4
−
1
8
n
≤
1
2
+
∑
k
=
1
n
−
1
1
−
k
2
n
2
≤
n
π
4
\frac{n\pi}4-\frac1{\sqrt{8n}}\le\frac12+\sum_{k=1}^{n-1}\sqrt{1-\frac{k^2}{n^2}}\le\frac{n\pi}4
4
nπ
−
8
n
1
≤
2
1
+
k
=
1
∑
n
−
1
1
−
n
2
k
2
≤
4
nπ
for every integer
n
≥
2
n\ge2
n
≥
2
.
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