To find the length of the rope at the beginning of the trick, we can write an equation based on the information given.
Starting with the original length of the rope \( L \), when the magician removes 3.6 meters, the remaining length of the rope becomes 3.71 meters. The equation can be formulated as:
\[ L - 3.6 = 3.71 \]
So, the appropriate equation to find \( L \) is:
\[ L - 3.6 = 3.71 \]