针对同一个图形,从不同的角度计算它的面积,并借助面积相等得到一个代数恒等式的方法,我们称为面积法.面积法作为数形结合思想中常用的方法,不仅可以验证乘法公式,而且在探求新知的过程中也有着广泛的应用.一、引例引例1如图1,现有边长为a、b、c的正方形纸片和长为b、宽为a的长方形纸片各若干张,用它们拼成如图2所示的长方形,则可以验证的代数恒等式是_____________. For the same graph, calculate its area from different angles, and get an algebraic equality method with the same area, which is called area method. As the commonly used method in the combination of number and shape, the area method can not only verify the multiplication formula, but also In the process of exploring new knowledge also has a wide range of applications.First, the cited example 1 as shown in Figure 1, the existing side length a, b, c square paper and the length of b, a width of a rectangular piece of paper each Zhang , Use them to form a rectangle as shown in Figure 2, you can verify that the algebraic identity is _____________.