Answer:
The height of the lamp post is 15 feet ⇒ 1st answer
Step-by-step explanation:
The ladder , the lamp post and the ground formed a right triangle, the length of the ladder is its hypotenuse (l), the height of the lamp post (h) and the horizontal distance on the ground between the base of the ladder and the base of the lamp post (d) are the legs of the triangle
By using Pythagoras Theorem ⇒ <em>the square of the hypotenuse is equal to the sum of the squares of the other two legs</em>
∵ l² = h² + d²
∵ The length of the ladder is 25 feet
∴ l = 25
∵ The ladder is placed 20 feet from the lamp post
- That means the distance between the base of the ladder and
the base of the lamp post on the ground
∴ d = 20
- Substitute the values of l and d in the Pythagoras formula
∵ (25)² = h² + (20)²
∴ 625 = h² + 400
- Subtract 400 from both sides
∴ 225 = h²
- Take √ for both sides
∴ 15 = h
∴ The height of the lamp post is 15 feet
