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Cordon sanitaire

Two perpendicular lines and a third line. Four circles are tangent to all three lines. Prove that their areas satisfy AB=CD.

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Solution

Solution by Jaihind Singh.

You may use the detail view below to convince yourself of the triangle similarity.

Visual solution

Proof without words by David Andriana.

Poem

cordon sanitaire
Is typical against many problems
Like racism or
Extreme right
But today
Against the Corona virus
With standard measures
Like testing
Contact tracing
Social distancing
Transmission reducing
To stop covid 19 spreading
Just a barrier
To the spread of anything

Bella

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