origin to arc/circle max distance?

origin to arc/circle max distance?

Hi everyone!

Is there a way to get a max dimension from center origin to the peak point of a circle/arc?

I tried using max distance on "distance between" report button but it does not get the measurement from the drawing and gives an entirely different number.

Is there any other way than max distance like vb script or I am just doing this entirely wrong? Please feel free to correct me :)
Thank you!

(badly drawn illustration for reference)