Answer:
≈ 397 m
Step-by-step explanation:
Using Pythagoras' identity on the right triangle
The square on the hypotenuse is equal to the sum of the squares on the other 2 sides.
Let h represent the height of the balloon above ground, then
h² + 50² = 400², that is
h² + 2500 = 160000 ( subtract 2500 from both sides )
h² = 157500 ( take the square root of both sides )
h ≈ 397 m ( to the nearest metre )
