A scalene triangle has no equal sides so it has no lines of symmetry as a line of symmetry would divide the triangle evenly. Therefore, the answer is never. A scalene triangle NEVER has symmetry with respect to a line containing an altitude of the triangle.
The answer to this statement is FALSE. A Scalene triangle is a triangle with no equal side lengths, so a line that contains the altitude of the traingle divides the triangle into two triangles with different sizes, so it has no symmetry.
