The two "shapes" are not actually triangles, though they look like they are. This is because the hypotenuses of the green and the blue triangles have different angles of incline, so what look like hypothenuses of the big triangles are actually broken lines with two almost parallel segments each.
Shape A is actually slightly concave, while B is a little convex. If you draw the two shapes one on top of the other, B will slightly stick out, with the difference being a rombus-shaped area that is exactly one square unit in area. |