STEP BY STEP SOLUTION:
Let's denote:
- h as the height of the piscucha above the ground at a given moment,
- d as the distance between Juan's hand and the point directly below the piscucha (which is 58 meters since he has released 58 meters of the thread),
- a as the angle of elevation (50° in this case).
The relationship between the height h, the distance d, and the angle of elevation a can be represented by the sin function:
 \[ \sin(a) = \frac{h}{d} \]  
In this scenario:
 \[ \sin(50°) = \frac{h}{58 \, \text{m}} \]  
Now, solve for h:
 \[ h = 58 \, \text{m} \times \sin(50°) \]  
Using a calculator:
 \[ h = 44.43 \, \text{meters} \]  
ANSWER:
Therefore, at the moment Juan has released 58 meters of the thread, the piscucha is  \( 44.43 \, \text{meters} + 1.68 \, \text{meters} = 46.11 \, \text{meters} \)  above the ground.