Answer:
Step-by-step explanation:
According to Pythagoras Theorem a² + b² = c²
And the questio is having a right triangle in it so,
(Height of the building)² + (Length of the shadow)² = (The distance from the top of the building to the tip of the shadow)²
⇒ a² + (12)² = (20)²
⇒ a² = (20)² - (12)²
⇒ a² = 400 - 144
⇒ a² = 256
⇒ a = √256
⇒ a = 16
