Find the total distance.
Find the total distance of what?
Are you maybe saying that v(t), which usually stands for "velocity", is actually a position function of some sort, and you're needing to find the total distance travelled by something or other over some time frame (perhaps the interval noted)?
I know you're suppose to take the absolute value of the function when it is negative and add to the positive.
Are you maybe saying that you need to take the absolute value of something, perhaps then splitting one function into pieces, and then adding the results of whatever you're doing to the pieces? Or are you really adding two different functions, one of which is an absolute value?
i split the integral into two, from 0 to 3pi/4 amd from 3pi/4 to 5pi/4. and solved but answer was wrong. i think i may have my limits of integration wrong when splitting into two.
You split what
integral into two? How did you define the integration limits? What did you get for your answer? On what basis do you think your answer is incorrect?
Please reply with the full and exact text of the exercise, the complete instructions, and a clear listing of your efforts so far, so we can tell what is going on. Thank you.