Similarity of figures
First, try to guess a figure that has an area equal to the total area of the tangram pieces. For this, take into account the figure similarity notion, because the given shadow image may not correspond - and it usually doesn't - to the full size of the image to be built with the game pieces. This means that the player must adapt the scale of the initial image to the size of the pieces being used.
The image above contains three similar figures with the same shape but different areas. Which one of them has the same area as the total of the tangram pieces?