This is a right triangle
It's called a right triangle because it has one right angle and two acute angles
This is an Obtuse triangle
The obtuse triangle has one obtuse angle and two acute angles that's way it's called an obtuse triangle.
The Scalene Triangle
The scalene triangle has no congruent sides or angles.
This is the isosceles triangle
The isosceles triangle it has two congruent sides and angles.
A four sided polygon.
The sum of all angles are 360 degrees.
Opposite sides congruent
Opposite angles congruent
Opposite sides parallel