Browse · MATH
Printjmc
geometry senior
Problem
Let be a regular hexagon. Let , , , , , and be the midpoints of sides , , , , , and , respectively. The segments , , , , , and bound a smaller regular hexagon. Let the ratio of the area of the smaller hexagon to the area of be expressed as a fraction where and are relatively prime positive integers. Find .
Solution
Let be the intersection of and and be the intersection of and . Let be the center. Let (without loss of generality). Note that is the vertical angle to an angle of regular hexagon, and so has degree . Because and are rotational images of one another, we get that and hence . Using a similar argument, , and Applying the Law of cosines on , Thus, the answer is .
Final answer
11