how to remember the "sign conventions of coordinates" easily . Introduction to Three Dimensional Geometry. For the measurement of all the distances, the optical center of the lens is considered. Share 0. Copyright © 2020 Applect Learning Systems Pvt. To remember sign conventions, you need to visualize the octant with corresponding axis (positive or negative sign). Ltd. All rights reserved. 1st quadrant=x=+(positive) y=+(positive) 2nd quadrant=x=-(negative) y=+(positive) 3rd quadrant=x=-(negative) y=-(negative) 4th quadrant =x=+(positive0. New Cartesian Sign Convention is used to avoid confusion in understanding the ray directions. When the distances are measured opposite to the direction of the incident light, they are considered to be negative. y=-(negative) 1 ; View Full Answer thanx for your help. document.write('This conversation is already closed by Expert'); look at the table, find a way to easily remeber it,draw d table when ur solving the sum nd ,automatically t will cum into memory. Sign Conventions. There is no standard rule to remember sign conventions in octant. Refer to the diagram for clear visualization. To remember sign conventions, you need to visualize the octant with corresponding axis (positive or negative sign). thanx in advance ^_^ Share with your friends. There is no standard rule to remember sign conventions in octant. Is there any trick to remember the sign conventions in each octant???????