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The shortest distance between two points is the straight line, connecting the points.
Surely, the hummingbird, being a disciplined rational creature, will choose the straight line to fly.
So, this problem is about a triangle.
You may even make one step forward and to see (or to guess/to recognize) a right-angled triangle here.
As soon as you identify a right angled triangle, apply the Pythagorean formula
d =
=
=
= 13 meters. ANSWER
(5,12,13) is a Pythagorean triple, next after (3,4,5).
Solved.