[tex]\huge{\boxed{25}}[/tex]
The radius is the distance from the center of the circle to its edge.
The diameter is the distance from one point on the edge to the opposite point on the edge, so it is twice as much as the radius.
This means we just need to multiply the radius by two to get the diameter. [tex]2r=d[/tex]
[tex]2(12.5)=d[/tex]
[tex]\boxed{25}=d[/tex]
