A triangle.
Every triangle has three sides. If it has any number of sides other than three, then it isn't a triangle.
A triangle that has three equal sides, and therefore three equal angles, is called an equilateral triangle.
A triangle can never have three right angles
Tri means three. And there are three angles to a triangle.
octogon * * * * * An obtuse angled triangle is a plane figure which is bounded by three straight sides, such that one of its angles is in the range (90, 180) degrees. By definition, all triangles can have only three sides and three vertices, so an eight triangle cannot exist.
That would be a right angle triangle that is isosceles.
A triangle.
An octahedron is a three-dimensional geometric shape with eight faces, each of which is an equilateral triangle. It is a polyhedron with eight vertices and 12 edges.
That is the definition of a triangle. If it did not have three sides it would not be a triangle. If it did not have three angles, it would not be a triangle.
A triangle.
A triangle with three sides is a polygon.
They are both shapes and an octagon can be made up of six or more triangles. Other than that they are not similar. A triangle must have three sides. An octagon must have eight sides.
An equilateral triangle is a triangle in which all three sides are equal. An example is a triangle with 60o in all three corners.
A triangle with three congruent angles
a triangle is a polygon with three sides.
It impossible for a triangle to have three acute angles. * * * * * What? A triangle most certainly can have three acute angles. Such a triangle would be called an acute-angled triangle!