Answer:
The height of the flag pole will be = 18.96 ft.
Step-by-step explanation:
See the attached diagram.
AB is the flag pole and the length of the shadow is AC.
Now, Δ ABC is a right triangle and has AB = 3x ft., BC = 20 ft. and AC = x ft.
So, applying Pythagoras theorem ,
AB² + AC² = BC²
⇒ (3x)² + x² = 20²
⇒ 10x² = 400
⇒ x² = 40
⇒ x = 6.32 ft. (Approx.)
So, the height of the flag pole will be = 3x = 3 × 6.32 = 18.96 ft. (Answer)
