"Úsáidtear cruthanna cosúil le triantáin, ciorcail agus dronuilleoga i matamaitic."
Translation:Shapes like triangles, circles and rectangles are used in mathematics.
The people reading you comments in these discussions are ordinary users, just like you, and we have no idea what word you typed in, so your repeated "not true" comments are little more than digital graffiti - "Pat75024 woz here".
If you used an word that isn't in Duolingo's vocabulary, share it with the other users. We may learn something new, or we may have insight into why Duolingo didn't accept your answer, in which case you might learn something new.
But repeatedly posting content free "not true" comments is wasting your time, and the time of the people who read your comments.