Trig Help: Identifying Challenges & Solutions

[wajed]

http://img132.imageshack.us/img132/8730/222fmf.jpg

what should I care of? what could cause problems to me?

 

[qntty]

the principal value of arcsine is not a full inverse of sine. Arcsine returns an angle in [-pi/2,pi/2] but x can be any angle. The fact that you book reminded you of is equivalent to saying that sin(x)=sin(y) does not imply that x=y. Take x=0 and y=2*pi for example.