Step-by-step explanation:
there is no "x" in the whole scenario.
you and your teacher mean "h" ?
this we get by using Pythagoras, because h, half of the baseline and one of the 51 m sides create a new right-angled triangle :
c² = a² + b²
c being the Hypotenuse (the side opposite of the 90° angle). a and b are the legs.
so, for that new inner triangle we have then
51² = h² + (48/2)² = h² + 24²
2601 = h² + 576
h² = 2025
h = 45 m
