Okay, so I'm having trouble with this problem.

at time t in seconds, a particle's distance s(t) , in centimeters, from a point is given by s(t)=4+3sint. What is the average velocity of the particle from t=pi/3 to t=7pi/3?

I got...

4+3sin(pi/3)=6.59807...

4+3sin(7pi/3)=6.59807...

Since they equal the same thing, if i were to put it into the equation

s(b)-s(a)/b-a

it equals 0, and i have a feeling that's not right...