To find the radius of a circle given its diameter, you need to use the relationship between the diameter and the radius. The radius \( r \) is half of the diameter \( d \). Mathematically, this can be expressed as:
[tex]\[
r = \frac{d}{2}
\][/tex]
Given the diameter \( d = 85 \) yards, follow these steps:
1. Substitute the value of the diameter into the formula:
[tex]\[
r = \frac{85}{2}
\][/tex]
2. Perform the division:
[tex]\[
r = 42.5
\][/tex]
So, the radius of the circle is [tex]\(\boxed{42.5}\)[/tex] yards.
