How to find the area of a circle by using circumference

A = C2 / (4 π).

Step-by-step explanation:

1. The area of a circle is given by the formula A = π r2, where A is the area and r is the radius. The circumference of a circle is C = 2 π r.

2. If we "solve for r" in the second equation, we have r = C / (2 π ). Now we use this to replace r in the first equation: A = π [ C / (2 π ) ]2.

3. When we simplify this, we get A = C2 / (4 π).

Interval Notation:

( − ∞ , ∞ )

Step-by-step explanation:

Set-Builder Notation:

{ x | x ∈ R }