I'm having trouble with this

Find a vector function that describes the border of the region in the first quadrant limited by y=4x, y=x,y=1/x, parametrized counterclockwise and find a tangent vector in (3/4, 4/3). In what points can you not define a tangent vector to the given curve? Justify.

I'm still stuck on the first part. I thought maybe giving a function by parts but I can't figure out how to do it.