An introduction to mathematics, by A. N. Whitehead.

CHAPTER XIII
TRIGONOMETRY
TRIGONOMETRY did not take its rise from
the general consideration of the periodicity of
nature. In this respect its history is analogous to that of conic sections, which also had
their origin in very particular ideas. Indeed,
a comparison of the histories of the two
sciences yields some very instructive analogies
and contrasts. Trigonometry, like conic sections, had its origin among the Greeks. Its
inventor was Hipparchus (born about 160
B.C.), a Greek astronomer, who made his
observations at Rhodes. His services to
astronomy were very great, and it left his
hands a truly scientific subject with important
results established, and the right method of
progress indicated. Perhaps the invention
of trigonometry was not the least of these
services to the main science of his study. The
next man who extended trigonometry was
Ptolemy, the great Alexandrian astronomer,
whom we have already mentioned. We now
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