All you need to know is that sin(x) is the y-value of the coordinate point and cos(x) is the x-value of the coordinate point. From here, tan(x) is just sin(x)/cos(x).
That's three of them already. sec(x) is 1/cos(x), csc(x) = 1/sin(x) and cot(x) = 1/tan(x).
Just to recap:






And you are done!