The correct answer is: "He developed mathematical principles"
René Descartes (1596 – 1650) was a French philosopher, mathematician, and scientist who lived more than 20 years in the Dutch Republic and was one of the main figures of the Dutch Golden Age.
His great influence in mathematics has been his major contribution to the Scientific Revolution, although his work in philosophy is outstanding too. He developed the the Cartesian system of coordinates. He is considered the father of analytical geometry, which connects both algebra and geometry and which has been used in the development of infinitesimal analysis and calculus .
Stone mason and concrete but their concrete that they used was one of a kind but nobody knows their recipey to make it
They were mostly brought by slaves who were taken to the Americas. They talked to their young ones because there was a high degree of oral tradition, and they would teach them things about life based on the folktales from West Africa, and it eventually became an integral part of the African-American identity in the United States.
President Roosevelt and President Hoover differed in their approaches to dealing with the Great Depression because Roosevelt did many things to get the economy back in shape, while Hoover wanted to tackle the problem, but didn't want to get in depth with it.
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President Hoover had an impression that the stock market crash during 1929 was just a simple error in the market, and that it could easily be fixed. He said that it would be fixed if everyone acted normal and act like the stock market crash never happened. The government intervention for him was not a solution.
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President Roosevelt became president right after Hoover, and he noticed the problem the stock market crash had on people in the economy. The thing that he did is that he made a lot of public works projects. For example, the Works Projects Administration, was a organization which gave people short-time employments to keep them on the right track, and get the stock market crash off their minds and give them some income. He also made "bank holidays" which didn't allow people to take all of their money out of their bank account. He was doing many things to fix the economy from the Great Depression.
