Jul 13, 2024
Both the triangles have the side-ratios, 3,4,5. the bigger one has a multiple factor of 5, the smaller one, 4. Thus (1/2)* 3*4*(5*5+4*4)=246 for the white area, ergo 154. (Same as Mr. Kibasa, although he did not explain where the 13 and 16 sides came from.)