Find the area of the black regionFind the area of the black region accurate up to 3 decimal places. (A=?, a=20, b=10)
Correct answers: 31
The first user who solved this task is Sanja Šabović.
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Cuyahoga River fireIn 1969, in America, oil-sodden floating debris on the Cuyahoga River ignited (perhaps by sparks from a passing train) and burned with flames reported up to five stories high. Although fire-fighters extinguished the blaze in a half-hour or so, it caused $50,000 in damage. For a century the Cleveland, Ohio river had been an open sewer for industrial waste, through the times when factory production seemed more important than worrying about the environment. Several fires had happened in the prior hundred years, but attitudes changed to outrage as this time, national attention was aroused. It became one of several disasters that led to the Clean Water Act and the Environmental Protection Agency (EPA). Determined remedial action for decades since has resulted in cleaner water, and improving aquatic life.«