Identify and describe four crucial events in evolutionary history without which our current existence would have been highly unlikely. explain your reasoning clearly.
***note, this is an extended essay question, worth 40 points. the response should be formatted in multi-paragraph essay with attention to essay structure, grammar mechanics, and apa formatting.

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. 

Answer feldspar,quartz,mica and amphibole;

Answerbecause of improved transportation, communication, and other advantages;