A ladder 25 m long leans against a vertical wall…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A ladder m long leans against a vertical wall. Its foot is m from the wall. How high up the wall does the ladder reach?
Need a reminder? The key ideaShow
Pythagoras theorem: in a right triangle with the right angle at B, . The converse: if , the angle at B is a right angle. To find a hypotenuse, add the squares of the legs. To find a leg, subtract the square of the known leg from the square of the hypotenuse.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The right triangle. The wall, the ground and the ladder make a right triangle. The ladder, m long, is the hypotenuse.
Step 2. The theorem. .
Step 3. The square root. .
Answer: the ladder reaches m up the wall.
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