Keeping this in consideration, how is a square and triangle the same?
They are both polygons. They are polygons with the fewest and second fewest possible number of sides. If the triangle were equilateral, they would both have sides of equal length and each would have internal angles of equal size (90 and 60 degrees respectively for square and triangle).
Secondly, why is a triangle called a square? That's because you call a square a Quadrilateral. Moreover, a figure with 3 angles and 3 fixed, corresponding joining sides is called a Triangle. Thus, your statement “Triangle is called a triangle” itself is null and invalid as we call such shape a triangle and not a 'Triangle' a triangle.
Also question is, can you make a square with 3 triangles?
If one means dividing a square into three triangles of equal area, the answer is NO. Simple answer is that a square has four sides and each of those sides must also be at least a part of one of the triangle sides. If a triangle 'consumes' two of the square's sides, an equal triangle must consume all of the other two.
What does a triangle and a square have in common?
A right triangle, a square and a rectangle have only one thing in common and that is one angle is 90 degrees. The differences between them are: A triangle has 3 angles while a square and a rectangle have 4 angles each. A triangle has 3 medians while a square and a rectangle have 2 diagonals each.
