I'm rotating the reference frame by 45° anti-clockwise.
We're splitting UT into vertical and horizontal distance.
∴ By 45-45-90 triangle we get UV = UT = 2.8 / √2 = 2.8/1.4 = 2 km.
∴ The vertical distance between start point and end point is = 8 - 2.8 - 2
= 3.2 km
And the horizontal distance between start point and end point is = 8 - 5 - 2
= 1 km
Therefore, The distance between starting and ending point will be the hypotenuse of right angle triangle with perpendicular sides 3.2 and 1.
∴ Required Distance = √ ( (3.2)2 + (1)2 )
= √ (10.24 + 1)
= √ (11.24)
= 3.35