A ladder 29 m long leans against a vertical wall with its foot 20 m from the wall. How high up the wall does it reach?
Answer and explanation
Correct answer: B. 21 m
- Step 1: The ladder is the hypotenuse: 29^2 = 20^2 + h^2. Step 2. h^2 = 841 - 400 = 441, so h = 21 m. Answer: 21 m. Why not the others: 9 m: Subtracting the lengths ignores the right angle. 49 m: Adding the lengths ignores the right angle. 22 m: That is one more than the height the theorem gives.
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