Two of the main economic activities in the guianas are

Two of the main economic activities in the Guianas are fishing and farming.

Explanation:

The Guianas are made up of five closely placed yet distinct territories, namely French Guiana, Guyana (British Guiana), Suriname (Dutch Guiana), Spanish Guyana (comprising of Amazonas, Bolivar, and Delta Amacuro states of Venezuela), and Amapa in northern Brazil (Portuguese Guiana). All the territories are predominantly reliant on agriculture and fishing for their food and economic gains. The climate here is favorable for the growth of rice, sugarcane, corn, etc.

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. 

Can you give us more information about this question and i will try to you as much as i can