Library / UKMT Maclaurin Olympiad /7 of 18

UKMT Maclaurin Olympiad, 2017

Combinatorics Difficulty 3.0 AMC 10/12 Prove it United Kingdom

How many triangles (with non-zero area) are there with each of the three vertices at one of the dots in the diagram?

Figure for this problem

We don't reproduce this publisher's solutions. Their own solution is here — work the problem first.

Want a route through all this instead of an archive? The track puts 2,604 problems in a working order, from Junior Challenge level to the IMO shortlist.

Source: UK Mathematics Trust, licensed © UK Mathematics Trust; past papers published free at ukmt.org.uk. Statement reproduced verbatim; metadata (topic, difficulty) added by this project. Solutions are the publisher's, linked not copied.