Find the arc length function for the curve measured from the point p

(a) Find the arc length function for the curve measured from the point P in the direction of increasing t and then reparametrize the curve with respect to arc length starting from P, and
(b) Find the point 4 units along the curve (in the direction of increasing t) from P.
r(t) = et sin t i + √2 et k, P(0, l ,√2)