Well what you are saying is correct, BUT....

I believe that Mark's preceding paragraph lays out the parameters for his following paragraph which you are talking about here.

He speaks of a triangle and the slope of such triangle having a base of 200 and a height of 100 would be.....blah blah blah(didn't feel like quoting).

Though he didn't clarify a 90 degree triangle I truly think this is what he meant.

So for his pyramid's side the base would be 400 units long where yours would be 200 units long.

Of course I can see how either would fit the posts with 1 being correct but not the other, either way you go.


Regards,
Lobo-hotei
lobo

Treat the earth well, It was not given to you by your parents, It was loaned to you by your children.
Native American Proverb