What type of punctuation signals the reader that words from the direct quote have been changed but the writer ?

That would have to be an ellipsis. When you say something like, "There was only one catch, and that was Catch-22, which specified that a concern for one's own safety in the face of dangers that were real and immediate was the process of a rational mind. Orr was crazy and could be grounded (blah blah)"(Joseph Heller 46).

OR

,"There was only one catch, and that was Catch-22,...Orr was crazy and could be grounded (blah blah)"(Joseph Heller 46).

aye how much for a gram of crack my homie jeremy needs it he is a horn dog.

the answer is

r ≈5.641

plug in the area of 100 yards into the equation

100=

divide each side by pi

≈ 31.8309=

take the square root of each side to find r

=r

r ≈5.641