Math Help - pitch of heklix

Hi.

can u tell me how to calculate pitch (i mean the vertical distance between two revolutions)of a helix with parametric equatios [2cost 2sint 6t]..?

dz/dt = 6

For example if we use meters and secs dz/dt = 6m/sec

between succesive revoultion t increases by 2pi

6m/sec*2pisecs =12pi meters between 2 succesive revolutions