HMMT 二月 2000 · 几何 · 第 9 题
HMMT February 2000 — Geometry — Problem 9
题目详情
- Ho w man y hexagons are in the gure b elo w with v erti es on the giv en v erti es? (Note that a hexagon need not b e on v ex, and edges ma y ross!) p
解析
- A hexagon an b e formed b y remo ving an y v ertex, remo ving all v erti es onne ted to that v ertex, and then remo ving an y edges onne ted to an y of the remo v ed v erti es, and these are the only hexagons in the diagram. Th us, sin e there are 10 v erti es, there are 10 hexagons in the gure b elo w.