Question

Hi

I'm Having a problem with a question in the application of the maximum and minimum (derivative)

I want to prove that the height = 3

and i had this relation ===> H = h + r

and h = - 2r !

I'm sure that (H) = 3 r
But I Can't get the answer of (h) in positive ... so can I use absolute Value ?

so that
abs( h = -2r)===> h = 2r ===> H = 3r

?????