Question

My triangle has only one line of symmetry what is it

Answer 1

If a triangle has a line of symmetry, that means it can be "folded" about the line of symmetry, and the sides and angles will match eachother(see attatched). This means that at least two sides and two angles are equal, which means our triangle is either iscosceles or equalateral.

Answer 2

Its a Isosceles triangle. No other triangle has only one line of symmetry except this one.