1. The problem is to find the area of a half circle. 2. The formula for the area of a full circle is $$A = \pi r^2$$ where $r$ is the radius. 3. Since we want the area of a half circle, we take half of the full circle's area: $$A_{half} = \frac{1}{2} \pi r^2$$. 4. This formula means you multiply the area of the full circle by one half because a half circle is exactly half of a full circle. 5. To find the area, you need to know the radius $r$ of the circle. 6. Once you have $r$, plug it into the formula and calculate the area. 7. For example, if $r=3$, then $$A_{half} = \frac{1}{2} \pi (3)^2 = \frac{1}{2} \pi 9 = \frac{9\pi}{2}$$. 8. This is the area of the half circle in terms of $\pi$. 9. You can approximate $\pi \approx 3.1416$ if you want a decimal value. 10. So, $$A_{half} \approx \frac{9 \times 3.1416}{2} = 14.1372$$. This is how you calculate the area of a half circle.