The figure shows a trapezoid ABCD with the
diagonals AC and BD meeting at O. EF, passing through O, is parallel to
the bases AD and BC. Prove that (1) O is the midpoint of EF, (2) EF is
the harmonic mean of AD and BC.
Thematic Poem: Exploring the Secrets of Trapezoids: Unraveling Properties with Intersecting Diagonals, Midpoints, Similarity, and Harmonic Mean
A trapezoid with intersecting diagonals,
challenge posed to the mathematical royals,
unravel the properties of this shape,
And reveal the
secrets it doth drape.
Through the midpoint O, the diagonals meet,
EF parallel to
bases, adds to the feat,
To prove that O divides EF in two,
Is a task that requires an insightful view.
With similar triangles, the path we tread,
parallel lines that we are led,
To the midpoint we prove that
we have arrived,
And a property of the trapezoid we have
But the journey's not done, the challenge remains,
the harmonic mean, and reap the gains,
Of a deeper
understanding of this shape,
And the knowledge that it doth
Through similarity, we find a way,
To express the lengths,
and make them play,
With the harmonic mean, a value so grand,
A new property of the trapezoid, we understand.
So we unravel the properties of this shape,
parallel bases, midpoints, and the tape,
That binds together
the secrets it holds,
And reveals to us, a world so bold.
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