Answer:
21.5 feet
Step-by-step explanation:
d = Distance of the bottom of the tower to the point of observation
x = Height of the top section of the tower
a = Height of bottom section
b = Total height of tower
[tex]\tan28^{\circ}=\dfrac{a}{d}\\\Rightarrow a=d\tan28^{\circ}\\\Rightarrow a=70\tan28^{\circ}[/tex]
[tex]\tan40^{\circ}=\dfrac{b}{d}\\\Rightarrow b=d\tan40^{\circ}\\\Rightarrow b=70\tan40^{\circ}[/tex]
[tex]x=b-a\\\Rightarrow x=70\tan40^{\circ}-70\tan28^{\circ}\\\Rightarrow x=70(\tan40^{\circ}-\tan28^{\circ})\\\Rightarrow x=21.5\ \text{feet}[/tex]
The height of the top section of the tower is 21.5 feet.
