We'll use the image below as a reference diagram. As you can see, the hexagon is divided into 6 triangles. And, one red line (center to point on the hexagon) would be the radius. Since we know that all of the triangles are equilateral triangles, and the hexagon is a regular hexagon, we know that one side of the hexagon is equal to 77m. (If the circle actually has a diameter (all the way across the circle), the answer would be 38.5m)
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Get one x+y=3 to y=x+3 and plug it into x-y=1 and you get x-(x+3)=1. Destitute the x and solve. Once you get what x equals plug it to to either equation for the value of x and solve for y