The answer is b. 448 cm²
The lateral area (LA) of a square pyramid is multiplication of half of the perimeter (P) of the base and slant height (s):
\(LA = \frac{1}{2} P*s\)
The perimeter (P) of the base which is square is the sum of its side length (a):
P = a+a+a+a =4a
Thus:
LA = 1/2(4a)s = 2as
It is given:
a = 11.2 cm
s = 20 cm
Therefore:
LA = 2as = 2 11.2 * 20 = 448 cm²
