If you have a supposedly right angle triangle rotated at a difficult angle and you need to prove that it is a right angle triangle using only the lengths of the sides of the triangle, can you say if you made an exact copy of the first triangle, same place same size, and rotated it 180 degrees, making a rectangle, and then measure from the original corner of the 'right angle' triangle, to the corner of the new 'right angle' triangle, and it is exactly the same as the original shape's hypotenuse, does that prove it is a right angle triangle?
Not necessarily........note this.....
Triangle ADC is the 180° rotation of the "supposed" right triangle ABC. Note that a parallelogram is formed - not a rectangle. The "hypotenuse" of each triangle - AC - is actually the diagonal of the parallelogram......!!!!
However, if ABC were a right angle....your supposition would be true.......a rectangle would be formed and the diagonal of this rectangle would be the two equal hypotenuses of both triangles.
Not necessarily........note this.....
Triangle ADC is the 180° rotation of the "supposed" right triangle ABC. Note that a parallelogram is formed - not a rectangle. The "hypotenuse" of each triangle - AC - is actually the diagonal of the parallelogram......!!!!
However, if ABC were a right angle....your supposition would be true.......a rectangle would be formed and the diagonal of this rectangle would be the two equal hypotenuses of both triangles.