# Geometry

Puzzles involving any geometry, including shapes, areas, distances, and angles

The coin rotation paradox is a famous math problem with an unintuitive solution:

If you roll a coin around the edge of another coin of the same size, from an external perspective, how many rotations does the coin make by the time it returns to its original position?

## Four Lines of Four Coins

Form four lines of four coins by moving exactly 3 of the coins below:

Rules:

• Coins cannot be stacked on top of one another.
• A line of five or more coins is still only considered one line.
• The centers of the coins must be precisely on the same straight line, but can be anywhere on the line.
• Lines can be any length, and can be horizontal, vertical, or diagonal.
Continue reading “Four Lines of Four Coins”

## Inscribed Squares

Above are two identical isosceles right triangles containing two inscribed squares.

In one, a perfect square has been inscribed such that two sides line up with the two legs of the right triangle. In the other, a perfect square has been inscribed such that one side lines up with the hypotenuse of the right triangle.

Is the inscribed square on the left larger or the one on the right?