Now draw a line from the center of the circle to one of the other two vertices of the triangle. That, together with the altitude just drawn, gives a right triangle with hypotenuse r (the radius of the circle) and one leg of length x/2. The other leg, along the altitude, again by the Pythagorean theorem, has length . But that altitude is that leg plus a radius: so that .
Squaring both sides, . Now the " " terms cancel giving . Dividing both sides by x, .
Now take r= 1 and r= 3438 to answer your questions.