Need math help with trigonometry !

1)    solve the equation on the interval, [0,2pi) .

6 tan^2 x -17 tanx +7 =0

2)  solve the equation on the interval, [0,2pi)

sinx = -2/3

3) 2 tan^2x -2 =0

4) olve the equation on the interval, [0,2pi)

   (cot u +1)(csc u -1) = 0

   u   = ?