1. **Problem statement:** Draw a circle and explain how to find its radius. 2. **What a radius is:** The radius is the distance from the center of a circle to any point on the circle. 3. **Formula to use:** If you know the diameter, then $$r=\frac{d}{2}$$ If you know the circumference, then $$r=\frac{C}{2\pi}$$ If you know the area, then $$r=\sqrt{\frac{A}{\pi}}$$ 4. **Important rule:** All radii in the same circle are equal because every point on the circle is the same distance from the center. 5. **How to find the radius in a picture:** - Find the center of the circle. - Measure from the center to the edge. - That distance is the radius. 6. **Example with diameter:** If the diameter is $10$, then $$r=\frac{10}{2}=5$$ So the radius is $5$. 7. **Example with circumference:** If the circumference is $18.84$, then $$r=\frac{18.84}{2\pi}$$ $$r\approx\frac{18.84}{6.28}=3$$ So the radius is about $3$. 8. **Final answer:** The radius is the distance from the center to the circle, and you can find it using $r=\frac{d}{2}$, $r=\frac{C}{2\pi}$, or $r=\sqrt{\frac{A}{\pi}}$ depending on what information you have.