Function hypotenuseFromAdjacent

Returns the hypotenuse length of a right-angle triangle, marked here

     .
>   ..
>  ...
> ....  opp
 .....
  adj

This is just:

opposite = Math.tan(angle) * adjacent

hypotenuseFromAdjacent(angleRadian, adjacent): number
Parameters
- angleRadian: number
- adjacent: number
Returns number