Do you know that sin^{2}(θ)+ cos^{2}(θ)= 1? Since you know sin(θ)= 1/3, you can use that to find cos(θ). Now, how is tan(θ) defined?

Take the arc sin of 1/3 - this will give you the angle, but it will be the principle angle (first quadrant). But, since Cos theta <0, you know it can't be in the first quadrant or fourth quadrant, so it must be in either the second or third quadrant. But, since sin theta is >0, it must be in the second quadrant. You should be able to get the correct angle from this info, and therefore the correct cosine and then - as was hinted before - remember the definition of tangent theta.