Answer:
None.
Step-by-step explanation:
The only possible restriction in the rational expression 
can originate in its denominator being zero for some values of a. However, since the denominator in this case (a^2+4) is always positive (and larger or equal to 4) for all values, no restrictions on the variable a exist.
1331= lwh or 1331= x^3
So take cube root of both sides and you will get 11.
Since the formula for area is length times width, the answer is 11x11 which equals 121.
So the square area of the base is 121mm^2
That point of concurrency is known as the incenter of a triangle.
