This is from a book named Problems in Calculus of One Variable by IA Maron. The text in the diagram reads:
p = 3a sin ф
arctan √2
3√2 a
p = 3√2 cos ф
Other pictures:
https://imgur.com/a/BRwB7R9
Editado el 17/04/2019 a las 19:59 por oxyde
Probablemente no es una fuente
Bump.
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