Semicircle Measurements 67F2E7

1. **Problem Statement:**\nWe have a semicircle with radius $r$. We need to find:\n- The diameter of the circle in terms of $r$.\n- The length of the semicircular arc in terms of $\pi$ and $r$.\n\n2. **Diameter of the Circle:**\nThe diameter $d$ of a circle is twice the radius.\n\nFormula: $$d = 2r$$\n\n3. **Length of the Semicircular Arc:**\nThe circumference $C$ of a full circle is given by:\n$$C = 2\pi r$$\nSince the arc is a semicircle (half of the circle), the arc length $L$ is half the circumference:\n$$L = \frac{1}{2} \times 2\pi r = \pi r$$\n\n4. **Summary:**\n- Diameter of the circle: $$2r$$\n- Length of the semicircular arc: $$\pi r$$