Equation Solvers - What Gives?

[sidius]

I am using a TI-89 to do the Page 5 Equation Solvers. Some times it works brilliantly. Other times it will return as many as 10 possible results.
How do I determine which result is correct?

[hansond10]

Whenever there is a trig function in the equation, it will generally have way multiple answers. So whenever trig is present, I completely skip attempting to solve it and just skip to graphing it. Graph the left side, graph the right side, the x value of the intersection is your answer. If done correctly, the graph should have multiple intersections. So unless specified (like, the smallest or negative or positive), always choose the smallest positive answer. This is because people generally care about the first Quadrant I answer, such as we want 45 degrees, not 225 or 405, even though for sin and cos, it would give you the same answer.

[AuSmith]

And, if your calculator doesn't find the intersection of two curves, you can graph the difference of the two functions and find a root. That way would probably be faster even if your calculator intersects two curves...