isosceles
We call it equilateral.
Equilateral triangles have three congruent sides. That's the definition of an equilateral triangle. If it doesn't have three congruent sides, then it's not an equilateral triangle.
it has one obtuse angle and none of the sides are congrent
square
No.
No. Usually only opposite sides are congruent.
a square
If the base of a triangle is 12, then the other two sides can be any length at all, just as long as they add up to more than 12. If they're congruent, then each one can be anything at all more than 6.
Trapezoid
is a regular pentagon if all its angles are congruent and is a general pentagon if they are not.
None normally unless it's an isosceles trapezoid then it will have 1 pair