HKMO1516GCQ1

Suppose there are three different parallel lines, L1, L2 and L3. Construct an equilateral triangle with only one vertex lies on each of three parallel lines. 假設有三條不同的平行線， L1、L2 及 L3。 構作一個等邊三角形，其中每條平行線只會有一個頂點存在。