Corey stepped back 59.71 feet to get a better view of the bird.
Explanation:
This is a right angled triangle. Let
be the angle of elevation.
Let the adjacent side of the triangle be x for the angle 
Let the opposite side of the triangle by y for the angle 
Thus,

Since, the height of the tree is 80 feet, 
To find the value of x, let us substitute
and 

Since, Corey moves back a few steps to gain a better view of the bird, the angle of elevation is 41°
Now, we shall find the x for
and 

To find how many feet Corey step back is to subtract the value of two adjacent sides, thus,

Thus, Corey stepped back 59.71 feet to get a better view of the bird.