Why are rain forests important to the world?
species found in the rain forest have been used for medical purposes.
rain forests are the natural habitat for 30 percent of the world's plant and animal species.
rain forests are a valuable food source for the world.
rain forests increase greenhouse gases.

The correct answer is rain forests increase greenhouse gases. I know for sure it's not the first or third answer. Rain forests are the habitats for many animal and plants but I'm pretty sure its over 50% not 30%. 

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.