Let, the breadth of mango grove = x m
Therefore, the lenght = 2x m
So, the area = x × 2x = 2x²
According to question, 2x² = 800
⇒ x² = 400
⇒ x = ±20
Since, the breadth of the mango grove can’t be negative, so the breadth = 20 m
Hence, the lenght of the mango grove = 2 × 20 = 40 m.