If you could show a diagram of some sort, or explain it, it would help but from how i understand it:
you can use either the Sin() Tan() or Cos() function. for example:
Sin(45)= The side opposite to the angle/ the hypotenuse
Cos(45)= side Adjacent to the angle/ the hypotenuse
Tan(45)= Opposite side to the angle/ side adjacent to the angle
Look at which side you need to find, and fill in the 84.6 where you need to. If you need hep with that please tell me. :)