Answer:
Height of flagpole = 571 ft
Step-by-step explanation:
Given:
Angle of elevation to the top of the flagpole is 55° .
Distance from the eyes to the base of flagpole = 400 ft.
To find the height of the flagpole.
Solution:
We can draw the situation as a right triangle as shown below.
In triangle ABC.

∠C= 55°
To find the length AB (height of the flagpole).
Applying trigonometric ratio :

Plugging in values.

Multiplying both sides by 400.


∴ 
Height of flagpole = 571 ft