An equilateral triangle with each of its vertices lying on one of the three concentric circles with radii 8, 15 and 17 respectively.[br]a) Could you think of how to construct it? Any variants given the point A is fixed?[br]b) By rotating the largest equilateral triangle at point A by 60[math]^\circ[/math] and Cosine Law, find the length of its side and its area [u]without using calculator[/u].[br]c) Could you think of another equilateral triangle with smaller area? How does it look like? Any variants given the point A is fixed?[br]