Hello!
First you have to find the height
You use the equation a^2 + b^2 = c^2
c is slant height
a is height
b is base length divided by 2
Put in the values
a^2 + 20^2 = 29^2
Square the numbers
a^2 + 400 = 841
Subtract 400 from both sides
a^2 = 441
Take the square of the number
a = 21
The height is 21
We now use the equation

l is length
w is width
h is height
Put in the values

Multiply
33600 / 21 = 11200
The answer is A)11,200 cubic centimeters
Hope this helps!