three-sided

He wants to cut our three-sided political game back down to two.

If you will look very carefully, you will see that the Acorn Shell is made of three-sided pieces, closely joined.

They were drawn up in a three-sided square, which looked pathetically small.

Their bases have three-sided plinths, and their capitals are enriched with stiff foliage and are three-sided above.

The latter may have almost any shape — a triangular point, one side of a three-sided prism is very convenient.

The three-sided pyramid would not have lent itself to such an arrangement.