trig
posted by Sarah on .
The displacement (in centimeters) of a particle moving back and forth along a straight line is given by the equation of motion s= 2 sin pi t + 3 cos pi t, where t is measured in seconds.
(a) Find the average velocity during each time period:
(i)[1,2]
(ii) [1,1.1]
(iii) [1, 1.01]
(iv) [1, 1.001]
(b) Estimate the instantaneous velocity of the particle when t=1.
Can someone please help me with this question, the trig functions have me confused. Please and thanks again.

PUt in the times given, first the final time,then calculate position, then put in the initial time, and calculate position.
avg velocity=(finalpositioninitialposition)/timeduration 
but how do we treat the cos and sin...just input them like that into the calculator or use radians?

and also for (b) is the answer 2pi

i got 3 for all part a can anyone verify that answer please