The Six Trigonometric Functions
From here you can use sin^2(x)+cos^2(x) = 1
Subbing in for cos(x) and solving for sin(x) you will get
sin(x) = sqrt(8)/sqrt(14)
Now use tan(x) = sin(x)/cos(x)
This should give tan(x) = sqrt(2), thisanswer is in the 1st quadrant.
tan is negative in the 2nd quadrant so tan(x) = -sqrt(2)