## Olympiad Corner: Which Number Is Erased?

A quadrilateral ABCD is given. The midpoint of side AB is equidistant from three other sides of the quadrilateral. Prove that the square of AB…

In a 4 x 4 array of 16 numbers, the sum of the numbers in each row, column, and diagonal is 1. Find the sum…

We have a series: tan(1)tan(2) + tan(2)tan(3) + … + tan(2019)tan(2020). What is its value? Here is a summation problem involving trigonometric functions. Do you…

Find the product of four consecutive numbers. Add 1 to this product. Extract the square root of this expression. What is the value? How to…

AB is perpendicular to BC. E and F are two points on BC such that AB = BE = EF = FC. Angles AEB, AFB,…

How many right triangles have their area double of their perimeter? How to find the exact number of such triangles? Do you have a mathematical…

A circle is inscribed in a triangle. And a circle is circumscribed about the same triangle. What is the ratio of their radii? Note that:…

Arithmetic mean is greater than or equal to Geometric mean. That is called AM – GM inequality. Here is a nice problem to show how…

An equilateral triangle is drawn inside a unit square. How can we find its area? Do you have a mathematical question to ask? Do you…

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