Question

whats the radius of this circle? 5 mm 15.7 mm 2.5 mm 1.25 mm

Explanation:

Step1: Identify radius from diagram

The circle's labeled line from center to edge (radius) is 2.5 mm.

Step2: Verify with circumference (optional)

Circumference formula: $C=2\pi r$. Substitute $C=15.7$ mm, $\pi\approx3.14$:
$r=\frac{C}{2\pi}=\frac{15.7}{2\times3.14}=2.5$ mm.

Answer:

B. 2.5 mm