Consider the equation of the tractrix y = a sech−1(x/a) − a2 − x2 , a > 0. (a) find dy/dx. dy dx = − a2 x√x+a√−x+a+ x √a2−x2 (b) let l be the tangent line to the tractrix at the point p. when l intersects the y-axis at the point q, show that the distance between p and q is a.