Two things:
1) The argument for arcsin(x) and arccos(x) requires
2) What does "rad(x)" mean?
1. as mentioned earlier, note that ...
therefore the value of x is restricted to ...
solving the equation ...
2. since arcsin(something) = arccos(something else) , the angle these two expressions equal can only be in quad I (why is that?)
let
since the angles are equal ...
so ...
solve for