Answer:
Yes it is valid
Explanation:
A square is a geometric shape which is also known as a Quadrilateral. This means that it has 4 sides.
For a square, it's 4 sides are equal to one another or we can put it in other words as the length of the 4 sides of a square are congruent to one another.
From the above question, we are asked that:
"If a square has a side length of 3, it's area is 9. Is it valid or invalid?"
The above statement is valid. This is because, the formula for the Area of a Square is given as
L × L = L²
Where L = Side length = 3
Area = 3 × 3 = 3²
Area = 9
Therefore, the statement is valid.