VeAnswer:This question belongs under mathematics
Explanation: It talks about angles and you might want to add a image to let us know what problem your working on
Answer:
In 1949, the prospect of further Communist expansion prompted the United States and 11 other Western nations to form the North Atlantic Treaty Organization . The Soviet Union and its affiliated Communist nations in Eastern Europe founded a rival alliance, the Warsaw Pact, in 1955.
It was the invention of the cotton gin.