快猫短视频

#24 Coin flips

set by James Grime

We can flip this triangle made of coins, from one pointing upwards to one pointing downwards, by moving three of the coins (coloured dark blue), as shown in the image below.

However, it is also possible to flip this triangle upside down by moving two coins. Can you find a way?

What about a triangle with four rows? What is the fewest number of coin moves needed to flip that triangle upside down?

How about bigger triangles? Is there a general rule?

Solution next week

 

#23 Four points, two distances

Solution

There are six possible ways to arrange four points so that the distances between pairs of points all take one of two values. This is the full set of possible solutions, although some solutions may be rotations or reflections of these.