The adjacent side divided by the hypotenuse is called the cosine of the angle, and is abbreviated to cos. For a given angle Ɵ, cosƟ = adjacent ÷ hypotenuse. This is written as a fraction.

Sine equals opposite over hypotenuse, cosine equals adjacent over hypotenuse, and tangent equals opposite over adjacent. SOH: Sin(θ) = Opposite / Hypotenuse CAH: Cos(θ) = Adjacent / Hypotenuse ...