Answer:
a.

b. 16
Explanation:
The area of a square is equal to the side length squared. Normally, the area of a rectangle is length times width but since all sides are equal in a square it is just the side times the side. This can be simplified to side length squared.
Since the side length is 4 the exponent form of the area is simply 4 squared or
.
Then, compute this by multiplying 4*4. This equals 16 cms square.