I’m pretty sure the answer would be 11.6 you use this formula a^2 + b^2 = c ^2 which would be 9+ b^2 = 42.25 then u subtract 9 from 42.25 which is 33.25 and then take the square root of that number which gives you 5.8. this number only measures the missing length of the triangle so to get the whole value of the line in the circle you have have to times it by 2 which then would be 11.6