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Periodic function – it is a proposition of a new definition – has as its domain the multiplicative group T = {z ∈C : |z| = 1} of complex numbers with module one. Therefore the graph of the function f : T → R lies on the cylinder T × R, and so the graph of cosine function is the ellipse (math formula)
W 1961 roku w katastrofie lotniczej zginął szwedzki polityk – sekretarz ONZ – Dag Hammarskjöld. Media światowe przypomniały wtedy wypowiedź jego matki: „Przy narodzinach twoich wszyscy się radowali, a jedynie ty płakałeś. Żyj tak, by po twej śmierci tyś się cieszył, a inni płakali”. Słowa te okazały się prorocze. Przy jego zwłokach znaleziono książeczkę Tomasza a Kempis De Imitatione Christi – o naśladowaniu...
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