9514 1404 393
Answer:
 10 +2√13 ≈ 17.2 meters
Step-by-step explanation:
The straight-line distance from the nest to the acorn is given by the Pythagorean theorem:
 d² = 6² +4² = 36 +16 = 52
 d = √52 = 2√13 . . . meters
The distance back to the nest is 4 m to the tree plus 6 m up the tree.
The round-trip distance to the acorn is ...
 2√13 +4 +6 = 10 +2√13 ≈ 17.2 . . . meters