1) Pull the hypotenuse of the left triangle to the upper left corner and simultaneously pull the hypotenuse of the right triangle to the upper right corner.

Until a square is formed.

Or like this: form a small square by making a vertical line to the two hypotenuses in the middle, and then pull the small triangles on the left and right sides into this small square to hide.

2) Pull the left vertical line to the left and the right vertical line to the right at the same time until the upper and lower arcs are drawn into a straight line.