Fact: the arctic latitudes are warming, which has released methane (a greenhouse gas) from thawing arctic permafrost. this has increased the rate of warming in the arctic. systems analysis would label this as
a) an open system
b) a closed system
c) a negative feedback loop
d) a positive feedback loop
e) an equilibrium condition

C. A negative feedback loop.

Explanation:

As we know the melting of Arctic ice caps and polar regions due to global warming impact, and the release of methane a harmful natural gas in the environment from the Arctic system has created a negative impact upon the ecological system impacting badly and hence destroying it. The occurrence of a negative feedback is a way of earth saying that its resource cannot no longer bear the pressure and hence a balance needs to be made within this system, so system analysis predicts show this negative feedback as a disturbance being created.

I'm pretty sure there's a geometry rule for   anyways, if the triangle is equilateral, and the circle is circumscribed, the circle is outside of the triangle.  to find the area, you need the radius.  the radius should be a straight line from the center of the triangle to any of it's points.  draw lines from the center of the circle to each of the triangle points.  draw three more lines from the center to the middle of the sides of the triangle.  you should now have six separate 30-60-90 triangles inside of your original triangle. use your 30-60-90 rules to solve for the radius, then the circumference.