Answer:
So draw a straight line. This measures as 180 degrees on your protractor. Align your protractor to the straight line, with the circle point in the middle of the line and notice the labels on the side. One of them, between 90 and 180 on the outer scale will measure as 135. Mark this on top of the paper, and remove the protractor. When you remove it, extend your mark to the middle of your line, and this gives you an obtuse angle of 135 degrees. Be sure to recheck!
Explanation: