The primary reason for france and japan were interested in controlling parts of indochina in the 20th century was 1.-dominate the indian ocean. 2.-obtain valuable natural resources. 3.-stop the spread of communism. 4.-prevent spanish colonization.

2. Obtain valuable natural resources.

Explanation:

The main reason for the interest of France and the japan in order to control over the Indo and china was the availability of the resources in the country as the period of the 20th century was marked as the period of the large scale growth in terms of the trade and commerce and this lead to the economic diversity of the nation as form 1930 the France started to exploit this region for the tea, rice, the coffee, the pepper, the coal, and the zinc.

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. 

Answeroil-shale;