1960 IMO Problems: Difference between revisions
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=== Problem 1 === | === Problem 1 === | ||
Determine all three-digit numbers <math>N</math> having the property that <math>N</math> is divisible by 11, and <math>\dfrac{N}{11}</math> is equal to the sum of the squares of the digits of <math>N</math>. | |||
[[1960 IMO Problems/Problem 1 | Solution]] | [[1960 IMO Problems/Problem 1 | Solution]] | ||
=== Problem 2 === | === Problem 2 === | ||
For what values of the variable <math>x</math> does the following inequality hold: | |||
<cmath>\dfrac{4x^2}{(1 - \sqrt {2x + 1})^2} < 2x + 9 \ ?</cmath> | |||
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In a given right triangle <math>ABC</math>, the hypotenuse <math>BC</math>, of length <math>a</math>, is divided into <math>n</math> equal parts (<math>n</math> and odd integer). Let <math>\alpha</math> be the acute angle subtending, from <math>A</math>, that segment which contains the midpoint of the hypotenuse. Let <math>h</math> be the length of the altitude to the hypotenuse of the triangle. Prove that: | In a given right triangle <math>ABC</math>, the hypotenuse <math>BC</math>, of length <math>a</math>, is divided into <math>n</math> equal parts (<math>n</math> and odd integer). Let <math>\alpha</math> be the acute angle subtending, from <math>A</math>, that segment which contains the midpoint of the hypotenuse. Let <math>h</math> be the length of the altitude to the hypotenuse of the triangle. Prove that: | ||
<center><math> | <center><math> | ||
\tan{\alpha}=\frac{4nh}{(n^2-1)a}. | |||
</math> | </math> | ||
</center> | </center> | ||
Revision as of 08:37, 28 October 2007
Problems of the 2nd IMO 1960 Romania.
Day I
Problem 1
Determine all three-digit numbers
having the property that
is divisible by 11, and
is equal to the sum of the squares of the digits of
.
Problem 2
For what values of the variable
does the following inequality hold:
Problem 3
In a given right triangle
, the hypotenuse
, of length
, is divided into
equal parts (
and odd integer). Let
be the acute angle subtending, from
, that segment which contains the midpoint of the hypotenuse. Let
be the length of the altitude to the hypotenuse of the triangle. Prove that: