| TRIGON | Old word for a three-sided polygon, such as an isosceles example; an ancient Greek or Roman lyre or harp; or, a group of three astrological signs belonging to the same element (6) |
| TRIPOD | An archaic word, from the Greek for "angle", for a three-sided shape; or, an ancient harp or lyre (6) |
| TRIANGLE | Polygon such as the isosceles with two of its three sides having equal length; or, an instrument in the percussion family (8) |
| TRIDENT | From the Latin for "three tooth", a word for a three-pronged spear (7) |
| ERATO | Muse of love poetry in Greek mythology, typically depicted holding a lyre or cithara (5) |
| NERO | Roman lyre player |
| SOS | Part of an isosceles triangle? HELP! (1,1,1) |
| ALONGSIDE | With what an isosceles triangle might have? (9) |
| EXEDRA | An ancient Greek or Roman colonnade, passage, portico or other outdoor element with a bench or seat as a place for debate or discussion (6) |
| TUNIC | A concentric layer of an onion; the coat of a sea squirt; a gym slip; or, an ancient Greek or Roman chiton (5) |
| STEREOBETE | From "to walk", a masonry foundation of a stone building; or, the substructure of an ancient Greek or Roman temple (10) |
| OARS | A trireme was an ancient Greek or Roman war galley with three banks of what? (4) |
| AMPHORA | An ancient Greek or Roman two-handled narrow-necked jar for oil, wine, etc (7) |
| DISCUS | Phonetically similar to "debate", a word for an ancient Greek or modern Olympian's lenticular throwing plate (6) |
| TRIREME | An ancient Greek or Roman war galley with three banks of oars (7) |
| ANTIQUE | Word for remains, including sculpture, from the ancient Greek or Roman world that is extended to mean anything old or collectable (7) |
| CHARIOTS | Ancient Greek or Roman cars for racing or warfare; or, any stately vehicles or triumphal carriages (8) |
| TRIG | Informal word for the branch of maths dealing with the properties of three-sided polygons (4) |
| TRIANGULAR | Artfully do a girl a turn in a three-sided relationship |
| TRIANGLES | Three-sided polygons (9) |
