• At least 1600 designs can be made using tangram pieces. Some of the designs are found on dishes, boxes, and in tables made in China in the 19th century.
• The square root of a negative number showwed up in the writings of Heron of Alexandria (Greece) around 50 AD. Mathematicians had trouble accepting the idea until hundeds of years later.
• In 628 AD, Hindu mathematician Brahmagupta found one of the solultions of a quadratic equation. His method was one which was used to develop the quadrtic formula.
• Factoring wasn't used to solve quadratic equations until 1631 AD.
• The Chinese are believed to be the first people to use negative numbers.
• The idea of zero arose separately in ancient India, Iraq, and Central and South America.
• In 1851, Jean Foucault used a pendulum to prove thet Earth rotates on its axis. His pendulum appeared to rotate because it stayed in the same place while Earth rotated.
• In 1990, Dr. Antonia Novello became the first woman and Hispanic to be Surgeon General. She chose a carrer in medicine after struggling with a serious health problem throughout her childhood and into her early twenties.
• Hubble's Law is an important direct variation used by astronomers. The law states that the more distant galaxies are moving faster.

Source: Integrated 2 Math Book