an isosceles trapeziod could be a quadrilateral because it has 4 sides and a quadrilateral has 4 sides
nope it is possible for a trapeziod to have three congruent sides
The base angles are congruent in an isosceles trapezoid
An isosceles triangle has two congruent sides.
Opposites sides of an isosceles trapezoid are congruent
The base angles of an isosceles triangle are congruent. The vertex angle of an isosceles triangle is not necessarily congruent to the base angles.
The legs are congruent.
If it doesn't have congruent angles, it's not an isosceles triangle.