Trigonometry

Excerpts

• Trigonometry

  The origin of trigonometry was practical; it was invented because it was necessary for astronomical research.

• Trigonometry

  Thus if the scale of a plan be an inch to a yard, a length of three inches in the plan means a length of three yards in the original.

• Trigonometry

  This peculiar property of the triangle, which is not shared by other rectilinear figures, makes it the fundamental figure in the theory of similarity.

• Trigonometry

  We have called $v$ the *sine* of $u$, and $w$ the *cosine* of $u$.

• Trigonometry

  It can be proved that $\pi$ is an incommensurable number, and that therefore its value cannot be expressed by any fraction, or by any terminating or recurring decimal.

• Trigonometry

  We are here in the presence of one of the fundamental processes of mathematical physics---namely, nothing less than its general method of dealing with the great natural fact of Periodicity.

• Trigonometry

  Characteristically enough conic sections were invented about $150$ years earlier than trigonometry, during the very best period of Greek thought.

Equations

Problems

No exercises in this chapter.