for all these types of triangles，we have only one formula to calculate its area，whereas we have learned that all different types of quadrilateral，have different formula for their areas，isn't this little unfair for triangles。
❤️初 中❤️数学❤️必背❤️公式❤️总结❤️（一）因式分解常用公式1、平方差公式：a²-b²=(a+b)(a-b)2、完全平方公式：a²+2ab+b²=(a+b)²3、立方和公式：a³+b³=(a+b)(a²-ab+b²)4、立方差公式：a³-b³=(a-b)(a²+ab+b²
