<p>I'm solving with the Barron's Math II book and in the answer section they're always saying to graph with the window x min = (number) x max = (number) and same for y min & y max. (different numbers)</p>
<p>What I don't understand is how I'm supposed to know when to change my viewing window's size. For example, here's a question where they tell us to use x[0, pi/4] and yp[-2,2], using any other viewing window size doesn't give the correct answer.</p>
<p>"Solve the equation sin 15x + cos 15x = 0. What is the sum of the three smallest positive solutions?"</p>
<p>Thanks</p>