Dissection of 3 Equal Squares into One Square

Problem
Dissect $3$ equal squares and use the pieces to make $1$ large square.

Solution

 * 3-Equal-Squares-into-1-Square.png

Bisect $2$ of the squares along their diagonals.

Arrange the right triangles so generated around the outside of the $3$rd square as shown.

Join the $4$ right angles of the $4$ right triangles.

The overlapping bits fit into the gaps.