When finding missing side measures in a right triangle.
Soh = (Sine = Opposite / Hypotenuse)
Cah = (Cosine = Adjacent / Hypotenuse)
Toa = (Tangent = Opposite / Adjacent)
There are also reciprocals for these values:
Cho (Cosecant = Hypotenuse / Opposite)
Sha (Secant = Hypotenuse / Adjacent)
Cao (Cotanget = Adjacent / Opposite)