Help with 3D Vector Non-Orthogonal Walls Problem

[lordnitro]

Hello everybody, so I've just joined, thought maybe you guys could help me out since I've been banging my head against my desk for a few days now. http://imgur.com/4FVpan3

(incase the inline image doesn't work: http://imgur.com/4FVpan3)

I'm stuck on problem 1.38. I know how to do it if the walls were orthogonal but since they aren't I'm stuck. I know how he's getting the 202 in the square root etc, but i have no idea where he's getting the 168cos(thetha) and subtracting it from. Can someone give me some tips about how to go about solving this problem? Thanks!

 

[KataKoniK]

Hello there! I understand your frustration with problem 1.38 and I'm happy to help. It looks like you're on the right track with understanding how to get the 202 in the square root. To answer your question about where the 168cos(theta) is coming from, it is most likely a result of using the Pythagorean theorem. Since the walls are not orthogonal, we can't simply use the length of the walls to find the diagonal. Instead, we have to use the Pythagorean theorem to find the diagonal length (represented by the 202 in the square root). This involves squaring the length of one wall and the height of the other wall, and then taking the square root of their sum. The 168cos(theta) is most likely the result of subtracting the squared length of one wall from the squared diagonal length, and then taking the square root. I hope this helps and good luck with the rest of the problem! Let me know if you have any other questions.