The Difference of Squares

Enter two whole numbers [math]a[/math] and [math]b[/math], [math] a>b[/math], in the input boxes. Click on segments [math]a[/math], [math]b[/math] and [math](a-b)[/math] to form [math]a^2[/math], [math]b^2[/math] and[math](a-b)^2[/math] Drag the blue square over the red square to align the lower left corners and click the "Subtract" button. Is it true that [math]a^2 - b^2 = (a-b)^2[/math]? Drag the slider "Rearrange" to see the area [math]a^2-b^2[/math] as the product [math](a-b)(a+b)[/math].