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If a straight line be cut at random, the square on the whole is equal to the squares on the segments and twice the rectangle
contained by the segments. (Euclid, Elements, II.4, 300 B.C.)
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(a + b)2 = a2 + b2 + 2ab
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If as many numbers as we please beginning from a unit be set out continuously in double proportion, until the sum of all
becomes prime, and if the sum multiplied into the last make some number, the product will be perfect. (Euclid, Elements, IX.36, 300 B.C.)
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If 1 + 2 + ... + 2n is prime, then 2n(1 + 2 + ... + 2n) is perfect |
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The area of any circle is equal to a right-angled triangle in which one of the sides about the right angle
is equal to the radius, and the other to the circumference, of the circle. (Archimedes, Measurement
of a Circle, 225 B.C.)
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A = 2pr·r/2 = pr 2
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The surface of any sphere is equal four times the greatest circle in it. (Archimedes, On the Sphere
and the Cylinder, 220B.C.)
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S = 4pr 2
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Rule to solve x3 + mx = n
Cube one-third the coefficient of x; add to it the square of one-half the constant of
the equation; and take the square root of the whole. You will duplicate this, and to one of the two
you add one-half the number you have already squared and from the other you subtract one-half the same...
Then, subtracting the cube root of the first from the cube root of the second, the remainder
which is left is the value of x (Gerolamo Cardano, Ars Magna, 1545).
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x =
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D in R - D in E aequabitur A quad. (Francois Viete, In artem analytican isagoge, 1590)
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DR - DE = A2
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