BrainTwister #25: Triangles in circles

#25 Triangles in circles

Set by Sam Hartburn

If you have six equally spaced points on a circle and join three of them, you can make three different triangles. (Two triangles are counted as the same if one is a mirror image or rotation of the other.)

How many different triangles can you make from seven equally spaced points?

And how many can you create from 12 equally spaced points?

Solution next week

#24 Coin flips

Solution

A triangle with six coins can be made to point downwards by moving two of the corner coins to the opposite side, for…