Yes.
An [equilateral] triangle, square and hexagon are the only regular polygons which, by themselves, will tile a surface.
An acute triangle can be an isosceles triangle, but it doesn't have to be. An isosceles triangle can be an acute triangle, but it doesn't have to be.
isosceles triangle
A right triangle and an isosceles triangle have the fact that they are both triangles in common. A right triangle can also be an isosceles triangle.
An isosceles triangle is a triangle that has two equal sides.
Are isosceles triangle sometimes an equilateral triangle
You cannot. An isosceles triangle cannot be scalene and a scalene triangle cannot be isosceles. So an isosceles scalene triangle cannot exist.
how is an isoscelels trapezoid related to a isosceles triangle
In an isosceles triangle and an isosceles trapezoid, both base angles are congruent
An obtuse triangle is not necessarily isosceles, but it can be.
A triangle that has one right angle and is isosceles is called an isosceles right triangle.