初中几何教材在讲完两个三角形全等的判定方法后强调指出,有两边和其中一边的对角对应相等的两个三角形不一定全等.不一定全等,就是说可能全等,也可能不全等.例如,如图1,在△ABC 和△ABD 中,已知AB=AB,AC=AD,∠B=∠B,显然它们不全等;如图2,在△ABC 和△A′B′C′中,已知 AB=A′B′,AC=A′C′,∠ACB=∠A′C′B′=Rt∠,则△ABC ≌△A′B′C′(即“斜边、直角边”定理). After finishing the method of judging the two triangles in the junior high school geometry textbook, it is emphasized that two triangles with equal sides of the two sides and the opposite sides of the two sides are not necessarily equal. They are not necessarily equal, that is, they may be equal. Incomplete, for example, as shown in Fig. 1. In △ABC and △ABD, AB=AB, AC=AD, and ∠B=∠B are known. Obviously, they are not equal; in Fig. 2, at △ABC and △A’B In ’C’, it is known that AB=A’B’, AC=A’C’, and ∠ACB=∠A’C’B’=Rt∠, then ΔABC ≌ΔA’B’C’ (that is, oblique Edge, right-angle side “Theorem”.