---
tag: 08WFZP6P89
kind: concept
name: Sine and cosine
msc: [33B10, 26A09]
sources:
  - url: https://en.wikipedia.org/wiki/Sine_and_cosine
    locator: lead section
same_as:
  wikidata: Q13647261
  wikipedia: Sine and cosine
---

## Summary

Sine and cosine are the basic trigonometric functions. For an angle $x$, the point $(\cos x, \sin x)$ lies on the unit circle, and the two functions are periodic with period $2\pi$. The node [[sine and cosine|0WB57D9488]] gives the precise definition by power series.