1. The problem is to calculate the area of a circle given its radius. 2. The formula for the area $A$ of a circle with radius $r$ is: $$A = \pi r^2$$ 3. Important rule: The radius $r$ is the distance from the center of the circle to any point on its edge. 4. To find the area, square the radius (multiply the radius by itself) and then multiply by $\pi$ (approximately 3.14159). 5. For example, if the radius is 3 units: $$A = \pi \times 3^2 = \pi \times 9 = 9\pi$$ 6. This means the area is $9\pi$ square units, or approximately 28.27 square units. This formula works for any circle as long as you know the radius.