A ladder seen from the side is sliding down a wall. Prove that a fixed point on the ladder traces part of an ellipse.
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Solution

Poem
The sliding ladder
Made to climb up and down
Like in life
Some can climb
Some will fall down
Wishing the sky
Or fall on the ground
Some are frightened and don’t go under a ladder
And for others it does not matter
Climbing the rungs
Can be a goal
For both, spirit and soul
