Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
The cosine function (cos) is a mathematical function that relates an angle within a right triangle to the ratio between the length of the adjacent side and hypotenuse. It is commonly used in physics to determine component vectors.
Related terms
Trigonometry: Trigonometry is a branch of mathematics that deals with relationships between angles and sides in triangles.
Right Triangle: A right triangle is a triangle with one 90-degree angle.
Adjacent Side: In trigonometry, the adjacent side refers to the side next to an angle under consideration.