a pyramid whose base is an equilateral triangle 100 feet on a side and whose finished height is 80 feet is under construction. but due to economic realities, construction is stopped at a height of 57 feet. the resulting structure looks like the bottom part of the pyramid on the left-hand side of the back of a u. s. one dollar bill.

a. measure the volume of this truncated pyramid.
b. measure the volume of the unfinished part.