Global Coordinates (X,Y relative to the global origin of 0,0)
Global Coordinates: A (1,5), B (-6,2), C (-2,-5), D (4,-4), E (0,-2)

Local Coordinates (X,Y relative to another point)
Local Coordinates of A relative to B (7,3): from B go right 7 and up 3 to get to A
Local Coordinates of B relative to A (-7,-3): from A go left 7 and down 3 to get to B
Local Coordinates of A relative to D (-3,9): from D go left 3 and up 9 to get to A
Local Coordinates of A relative to E (1,7): from E go right 1 and up 7 to get to A

Click on the image to the left to access a video which demonstrates how to determine the coordinates of various points on a beam given distances and angles.

Being able to determine the coordinate geometry on a structure is very important.