The bisphenoids (the hemihedral forms of the tetragonal and rhombic bipyramids)., and the trigonal pyramid of the hexagonal system, are examples of non-regular tetrahedra (see Crystallography). [Please select]
0
Wings trigonal, forming a nearly horizontal angle with the body when the insect is at rest. [Please select]
0
_ Bill short, very straight, base trigonal, beyond attenuated to a very fine point; upper mandible above rounded, both entire. [Please select]
0
The horns are trigonal, laterally compressed and knotted on the upper edge. [Please select]
0
Supra-triangular space: in Anisoptera, an area just above the triangle, occupying nearly the same position as the quadrilateral of Zygoptera: hyper-trigonal space. [Please select]
0
Horns very large, depressed and sub-trigonal at the base, attached to the highest line of the frontals, inclining upwards and backwards, conical towards the tip and bending upwards; muffle large, square. [Please select]
Do you have a better example in your mind? Please submit your sentence!