Infinite
There can be only one pair of perpendicular lines in an isosceles triangle when it is a right angled isosceles triangle. A non right angled isosceles triangle has no pairs of perpendicular lines.
Perpendicular lines meet at a right angle so a right angled triangle has two lines which are perpendicular to eachother. However there are no parallel lines in a right angled triangle, or any triangles for that matter.
A scalene triangle that is not right angled.
Two.
No. Parallel lines are lines that extend in the same direction. In a triangle the lines go in different directions.
None !
3
There are no parallel sides in a right angle triangle
None normally but if it is a right angle isosceles triangle it will have 1 line of symmetry
A right angled triangle.
Yes, because you can notice that the right angled triangle has one right angle, so its only 1 perpendicular line. Hope this helped :D
it has only one line of symmetry.