1. **State the problem:** Find the surface area of a sphere given its radius $r$. 2. **Formula:** The surface area $A$ of a sphere is given by the formula: $$A = 4\pi r^2$$ 3. **Explanation:** This formula comes from geometry where $\pi$ is approximately 3.14159 and $r$ is the radius of the sphere. 4. **Intermediate work:** To find the surface area, square the radius $r$ to get $r^2$, then multiply by $4\pi$. 5. **Final answer:** The surface area of the sphere is $$A = 4\pi r^2$$ This means if you know the radius, just plug it into this formula to get the surface area.