Sine, cosine, tangent: there is a hint to know when to use it- soh cah toa
Soh stands for sine= opposite over hypotenuse
Cah stands for cosine= adjacent over hypotenuse
Toa stands for tangent= opposite over adjacent
So depending on which sides you have, you either pick sine, cosine, or tangent.
Hope that helped!!!!
Have a great day!!!!!!