The position s (in metres) of a bus moving along a straight road after t seconds is given by s(t)=tsint+t.
a. (i) Find the velocity v(t) of the bus at any time t.
b. (ii) Calculate the instantaneous velocity when t=4π s.
c. (iii) Write the equation of the tangent to the graph of s versus t at the point corresponding to t=4π.