In order to create a covariance matrix for a given R DataFrame:

covariance_matrix <- cov(df)

## Steps to Create a Covariance Matrix for R DataFrame

### Step 1: Create a DataFrame

Here is the syntax to create a DataFrame in R with 3 columns:

df <- data.frame( A = c(45, 37, 42, 35, 39), B = c(38, 31, 26, 28, 33), C = c(10, 15, 17, 21, 12) ) print(df)

The resulted DataFrame:

```
A B C
1 45 38 10
2 37 31 15
3 42 26 17
4 35 28 21
5 39 33 12
```

### Step 2: Build the Covariance Matrix

To build the covariance matrix in R:

df <- data.frame( A = c(45, 37, 42, 35, 39), B = c(38, 31, 26, 28, 33), C = c(10, 15, 17, 21, 12) ) covariance_matrix <- cov(df) print(covariance_matrix)

The resulted covariance matrix:

```
A B C
A 15.8 9.60 -12.00
B 9.6 21.70 -17.25
C -12.0 -17.25 18.50
```

In case needed, the following guide explains the steps to create a correlation matrix in R.