According to the diagram, what is the altitude?

1. You can solve this exercise and find the altitude, by applying the Pythagorean Theorem, which is:
 
 h²=a²+b²
 
 "h" is the hypotenuse of the right triangle (h=500 m).
 "a" and "b" are the legs of the right triangle (a=400 m and b=x).
 
 2. You want to calculate the altitude "b", so you must clear it from the equation:
 
 h²=a²+b² 
 b²=h²-a²
 b=√(h²-a²)
 
 3. When you substitute the values of "h" and "a" into the formula, you obtain:
 
 b=√(h²-a²)
 b=√(500 m)²-(400 m)²
 b=300 m
 
 What is the altitude?
 
 The answer is: 300 m