Uh... come again? Maybe I'm not seeing it, but is there more to this problem? It this part of a bigger problem?
EDIT: Do you mean this:
given without using calculator,find the values of .
I'm getting 2 answers:
I started by using the tangent double identity:
... solved for , then rewrote in terms of .
EDIT: I originally thought that both answers I wrote above were plus-minus, but I forgot that is positive, which means that the angle has to be in Quadrants I or III. So is between 0 and 45° or between 90° and 135°, and for those values of , sine is positive.