La discriminación racial en Estados Unidos era permitida gracias a uno de las siguientes doctrinas: El Destino Manifiesto

La Doctrina Monroe

Separate by Equal

La Guerra Fría

Racial discrimination in the United States was allowed thanks to one of the following doctrines:

Manifest Destiny

The Monroe Doctrine

Separate by Equal

The Cold War

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 b is the answet

Earthquake waves that vibrate from side to side and up and down only through solids are known as "seismic waves."hope my answer has you : )