---
title: "Trigonometric Function — AP Calc Definition & Exam Guide"
description: "Trigonometric functions like sine and cosine relate angles to ratios and cycle through derivatives, which is why they anchor integration by parts in Unit 6."
canonical: "https://fiveable.me/ap-calc/key-terms/trigonometric-function"
type: "key-term"
subject: "AP Calculus AB/BC"
---

# Trigonometric Function — AP Calc Definition & Exam Guide

## Definition

Trigonometric functions are mathematical functions that relate angles and ratios of sides in triangles. Common examples include sine, cosine, and tangent.

## Review

### Related Terms

- Periodicity: Periodicity refers to how trigonometric functions repeat their values after certain intervals. For example, sine has a periodicity of 2π radians or 360 degrees.
- Unit Circle: The unit circle is a circle with radius 1 centered at the origin (0,0) on the coordinate plane. It helps visualize trigonometric values based on angle measurements.
- [Inverse Trigonometric Functions](/ap-calc/key-terms/inverse-trigonometric-functions): Inverse trigonometric functions undo trigonometric operations. They allow us to find angles when we know ratios of sides in right triangles.