Lets say I want to integrate sin from 0 to pi The answer is 2 But how do visualize it in terms of the graph? am I summing up the area under the graph? So it's like max value of 1 on the y axis While the x axis stretches from 0 to 3.14? If so, then why does doing the calculus in terms of cos (after integrating) give me the same result? What is the reason behind it? What am I doing essentially? Thanks!