理科第２１题别解４１１５００湖南双峰县教研室谢松其３４１１００江西赣县中学马跃进２３１２００安徽肥西师范学校万家栋７１０１１７陕西长安四中岳建良公差为ｄ，则将（３），（４）两边平方相加化简得由熟知的三角形内角恒等式访（５）代入上式．分解得理科第21题别... Science 21th title solution 411500 Hunan Shuangfeng County Teaching and Research Office Xie Songqi 341100 Jiangxi Qixian Middle School Ma Yuejin 231200 Anhui Feixi Normal School Wanjiadong 710117 Shaanxi Chang’an Sizhong Yuejianliang Tolerance d, then will (3), (4) both sides The square addition and simplification have been replaced by the well-known triangular inner angle identity access (5). Decomposed science 21th topic...