Submitted by admin on Mon, 04/14/2014 - 23:38
definition:
A solid having four plane triangular faces; a triangular pyramid
sentence:
The new structure consists of 20 small crystalline tetrahedrons - pyramids with four triangular sides - that fit together a bit like sections of an orange.
In designing aircraft his use of tetrahedral structural elements inspired him to develop and patent a system of space frame architecture.
difficulty:
hard
toefl frequency:
1
toefl classification:
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