A triangle can have 0, 1, or 3 lines of symmetry depending on the type of triangle.
1. Equilateral Triangle: This type has 3 lines of symmetry. Each line of symmetry runs from a vertex to the midpoint of the opposite side, dividing the triangle into two equal halves.
2. Isosceles Triangle: An isosceles triangle has 1 line of symmetry. This line bisects the triangle and runs through the vertex opposite the base and the midpoint of the base, creating two congruent halves.
3. Scalene Triangle: A scalene triangle has no lines of symmetry, as all sides and angles are different and there is no way to divide it into two equal parts along any line.
In summary, the number of lines of symmetry in a triangle varies with its type: 3 for equilateral, 1 for isosceles, and 0 for scalene.