Examples from the Web for apothem
In any pyramid, the apothem is to half the base as the area of the four sides is to the area of the base.
A peculiarity of this pyramid is, that base is to altitude as apothem is to half base.
I have mentioned the above to show how very nearly these ratios agree with my exact ratio of 21 to 34 half base to apothem.
The "Apothem is a perpendicular from the vertex of a pyramid on a side of the base."