"He climbed into the canyon on April 26. He HAD GONE about five miles when he came to a section where a series of boulders were hanging...".

Sorry, I might sound stupid, but why can't I write "he HAD BEEN GOING about five miles..."?

Because the term "He Had" is not used correctly in this sentence the correct wording would be "he had went out and gone 5miles when he saw the section where the series of boulders was hanging" this way the sentence makes more sense and sounds kinda smart and short

Explanation:

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

as for symbolic actions, the narrator's tearing down the wallpaper in an attempt to find the "woman" in the wallpaper represents her struggle to retain or regain her sanity.   the wallpaper has been part of her confinement and by her tearing it down, she is freeing herself from that confinement.