Which of the following does not contribute to increased air quality? a. the clean air act b. hybrid cars c. energy-efficient appliances d. use of cfcs

The correct answer is D. Use of CFCs

CFCs are very dangerous for the environment and destroy the atmosphere which in turn lowers air quality. They are commonly known as Freon due to a brand of CFCs found in fridges.

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.