Verify Unit length to y-axis from Tractrix Curve

[MxwllsPersuasns]

Homework Statement

The problem is described in the picture I've attached. It is problem number 6.

Homework Equations

Tangent line of a curve
Length of a curve

The Attempt at a Solution

I don't know why I'm so confused on what seems like it should be a relatively straightforward problem, but I am. I guess I would approach this problem by finding the tangent line at a point (say t=0) (though I forget the procedure to do that exactly) and then basically just show that the tangent line has length 1 from y = 0 basically?
- Also would I just like subtract the two points (i.e., the point on the curve where there is a tangent line and then the y-axis (y = 0)) or would it require the use of the formula for length namely the integral of the absolute value of the derivative of γ(t) from the y-axis to the point on the curve?

Any help with this would be greatly appreciated!

 

[LCKurtz]

It would help if you would type the statement of the problem instead of posting an illegible image.