HMMT 二月 2012 · 几何 · 第 5 题
HMMT February 2012 — Geometry — Problem 5
题目详情
英文原题
A mouse lives in a circular cage with completely reflective walls. At the edge of this cage, a small flashlight with vertex on the circle whose beam forms an angle of 15◦is centered at an angle of 37 .5◦ away from the center. The mouse will die in the dark. What fraction of the tot al area of the cage can keep the mouse alive? 37.5◦
解析
英文解析
- A mouse lives in a circular cage with completely reflective walls. At the edge of this cage, a small
° °
flashlight with vertex on the circle whose beam forms an angle of 15 is centered at an angle of 37 . 5
away from the center. The mouse will die in the dark. What fraction of the total area of the cage cankeep the mouse alive?
°