Answer: Archimedes go to sleep at 8.32 metres away from the rock.
Explanation:
Given that the rock beside which he slept was 5 meters tall
Height h = 5m
Angle Ø = 31 degree
To get distance x away from the rock, we will use trigonometry function. SohCahToa
TanØ = opposite/adjacent
Tan 31 = 5/x
x = 5/tan31
x = 8.32m