Can anybody help?

 Circumradius
The circumcircle of a triangle is a circle that passes through all of the triangle's vertices, and the circumradius of a triangle is the radius of the triangle's circumcircle. Circumcenter (center of circumcircle) is the point where the perpendicular bisectors of a triangle intersect.

R = { a b c } / { 4 r s } = { 3.16 * 3.16 * 2 } / { 4 * 0.721 * 4.162 } = 1.667, where r =inradius, s =semiperimeter.

Let

a, b  =  √10 

c = 2  

The circumradius can be found as

  (abc) / √((a + b + c)(b + c - a)(c + a - b)(a + b - c))

So we have

( 10*2) / √   [ ( 2√10 + 2) ( 2) ( 2 ) ( 2√10 - 2)  ]  =

20  /  √ [ (40 - 4) (4) ] = 

20 / √ [ 36 * 4]  =

20 / √144 =

20 /12  =

5/3   units

Thx Cphill