You are trying to take too big a step and need to go back and solve some simpler related problems, perhaps study some more math, talk to your friends, or talk to your teacher. You may be hesitant to do this since you are under time pressure, but continuing to spin your wheels is not getting you anywhere.
Keep in mind that being stuck does not mean that you will never be able to solve the problem, or that you are going to fail this course, or that you are a cosmic failure. It just means you have to back up and approach the problem anew.
Fine print, your comments, more links, Peter Alfeld, PA1UM