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1 May (Secondary)
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Pentakite
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Student Solutions
Teachers' Resources
$ABCDE$ is a regular pentagon of side length one unit.
The lines $AB$ and $DC$ are extended until they meet at another point, $F$.
Can you show that triangle $BFC$ is congrugent to triangle $DAC$?
Can you find a pair of similar triangles?
Can you use these results to find the length $DA$?
You can read more about the Golden Ratio in this
Plus Article
.
We are very grateful to the
Heilbronn Institute for Mathematical Research
for their generous support for the development of this resource.