SOH - CAH - TOA
Sine = Opposite/Hypotenuse
Cosine = Adjacent/ Hypotenuse
Tangent = Opposite/Adjacent
The opposite side is the one that forms the right angle and the other acute angle. Shortest side corresponds to the smallest angle.
The adjacent side is the one that forms the angle mentioned, but not the hypotenuse.
The hypotenuse is the longest side of the triangle; it corresponds to the 90° angle (only right triangles have a hypotenuse)
sin (H) = 12/15 = 4/5
cos (H) = 9/15 = 3/5
tan (H) = 12/9 = 4/3
sin (F) = 9/15 = 3/5
cos (F) = 12/15 = 4/5
tan (F) = 9/12 = 3/4