Which of the following characteristics is not true of cold fronts?
a. violent weather such as thunderstorms occur along them.
b. the temperature drops as they pass.
c. clear weather usually follows them.
d. they move more slowly than warm fronts.

A cold front is the transition zone where a cold air mass is replacing a warmer one
They move more slowly than warm fronts.
Because other three are characteristics of the  cold front  and they move faster than warm
so option D is correct
hope it helps

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.