I.

The formula for the arc length of a parametric curve is given by $$\int_{a}^{b} \sqrt{(dx/dt)^2 + (dy/dt)^2}\,dt$$.

II.

When computing the arc length, squaring the derivatives is unnecessary if the derivatives are already positive.

III.

The limits of integration correspond to the parameter values at the endpoints of the curve.

Which of the statements above are true?