Riddle 10 – The perfect Heptagon with diagonals
How many triangles of any size are in this Heptagon?
The Triangelog says you'll need to print it twice and even more.
"I will show my methods to solve
riddles 9+10 in part C of the book!"
Triangles counting fun pages - By Chen Nirran
Advanced riddles – 01 - http://www.triangelog.com/