The acceleration at time 5.5, we just have to say t is 5.5 and evaluate this function. 1 half, I'll just write.5 times e to the t over 4. t is 5.5. 5.5 divided by 4 and then times cosine of 5.5 divided by 4. Gives us.38. Did I do that right? We have.5 times e to the 5.5 divided by 4 times cosine. Sorry, I made a mistake.