Alright, lets get started.
Please refer the diagram I have attached.
The red line indicates the movement of student.
The movement of bird is indicated by orange line.
There will a right angle triangle made with sides measuring
One side will be = 0.5 miles
second side will be = [tex]1 - 0.2 = 0.8 miles[/tex]
The hypotenuse will be the orange one
So, using Pythagorean theroem,
[tex]c^2 = a^2 + b^2[/tex]
[tex]c^2 = 0.5^2 + 0.8^2[/tex]
[tex]c^2 = 0.25 + 0.64[/tex]
[tex]c^2 = 0.89[/tex]
Taking square root on both sides
[tex]c = 0.94[/tex]
So the bird has to fly 0.94 miles . : Answer
Hope it will help :)