Quadrature


From Encyclopedia Britannica (11th edition, 1910)

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Quadrature (from Lat. quadratura, a making square), in astronomy, that aspect of a heavenly body in which it makes a right angle with the direction of the sun; applied especially to the apparent position of a planet, or of the moon at first and last quarters. In mathematics, quadrature is the determination of a square equal to the area of a curve or other figure.