History of bifocals and trifocals
Benjamin Franklin, the early American statesman and inventor, is credited with creating the first multifocal lens for eyeglasses. Prior to Franklin's invention, anyone with presbyopia had to carry two pairs of eyeglasses — one for seeing distant objects and one for seeing up close.
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Reunified China by conquering the other warring states in 10 years. He then ruled the qin dynasty (221-206 bc) till his death with devastating purpose, completing the Great Wall and the terracotta Army.
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A rectangle is bounded by the x-axis and the semicircle y = √(25 - x²). What length and width should the rectangle have so that its area is a maximum?
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