The problem presents a formula for calculating the area $A$ based on variables $n$ and $d$. The formula is given by $A = \frac{n \cdot d^2}{4}$.

1. Problem Description

The problem presents a formula for calculating the area $A$ based on variables $n$ and $d$. The formula is given by $A = \frac{n \cdot d^2}{4}$.

2. Solution Steps

The formula provided is $A = \frac{n \cdot d^2}{4}$. There are no further calculations to be done since there are no given values for $n$ and $d$.

3. Final Answer

$A = \frac{n \cdot d^2}{4}$