What is the extent of zone III in the Philippine Plane Coordinate System?

• A. 119°30' to 122°30'
• B. 119°00' to 122°00'
• C. 120°00' to 123°00'
• D. 121°00' to 124°00'

Answer: (A)

In the Philippine Plane Coordinate System, each longitudinal zone is a 3-degree band. The boundaries are fixed lines that define where one zone ends and the next begins, so coordinates within a zone use that zone’s central meridian for the projection.

For this question, the convention used defines Zone III as spanning from 119°30' to 122°30'. That 3-degree interval is what keeps distortions manageable for mapping within that zone, and it aligns with the boundary meridians used in this system’s scheme. The other options shift the boundaries by a degree or more, which would place them outside the specified 3-degree band for Zone III in this reference.

Remember, different texts or editions may present the zone numbering slightly differently, but the essential point is that each zone is a 3-degree longitudinal strip bounded by fixed meridians.