Update AreaRec.java

[mathewjosephta]

1. Removed undeclared area variable in the getArea() method:
Instead of using a separate variable, you can directly return the result of length * breadth.

2. Changed setdimension to setDimension:
Following Java naming conventions (camelCase) for method names, the method was renamed to setDimension.

3.Consistent data types:
In the original code, you used float for length and breadth, so I ensured that getArea() returns float as well, for consistency.

4. Added sc.close():
It's a good practice to close the Scanner object after use to avoid resource leaks.