Question

According to sign convention, the distance which is measured in the direction of
incident light, to be taken as​

Answer 1

Answer:

All the distance are measured from the optical center. The distances measured in the direction of incident rays are positive and all the distances measured in the direction opposite to that of the incident rays are negative.

Explanation:

Answer 2

Answer:

All the distance are measured from the optical center. The distances measured in the direction of incident rays are positive and all the distances measured in the direction opposite to that of the incident rays are negative.