How many triangles are in this figure?
Count carefully! Let’s start at vertex A. Each of the 8 triangles listed below has four more like it, counting around the large figure.
| △AEF (△BAG, △CBH, △DCJ, △EDK) | △ADH |
| △AEG (& four more) | △AKC |
| △AFB (and so on…) | △ADC |
| △AEB | △AFG |
Each of these 8 represents five triangles, so the total number is 40.