Enlarge image
Photo: DER SPIEGEL
Three concentric circles are drawn on a sheet of paper.
Concentric means that all three have the same center point.
Your task is to construct an equilateral triangle with three corner points on the edge of one of the circles.
The sketch above shows such an equilateral triangle.
You can use compasses, rulers and, if you like, a protractor.
However, this is not absolutely necessary.
The radius of the circles is 7, 11 and 15, although slight deviations are permitted.
When designing, we use a 60-degree rotation that leads us almost directly to the triangle we are looking for.
The following photo gallery shows the solution step by step - please click on the first picture.
Then the other pictures and the corresponding description also appear.
I discovered this challenging geometry puzzle on the Euclidea website.
Many thanks to the mathematician Dierk Schleicher for the clever solution idea.
If you missed a puzzle from the past few weeks, here are the most recent episodes:
Pirates fight over 120 gold coins
December 31st wins
What time is it?
Pretty weird
The perfect egg
Cleverly asked
Enclosed by six circles
x, y unsolved
Floor plan with gaps
Wrong track