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北师大版数学教科书八年级上册(2013年7月第1版)“勾股定理的逆定理”表述为:“如果三角形的三边长a,b,c满足a~2+b~2=c~2,那么这个三角形是直角三角形.”这种表述没错,但是,在运用中常因此出现推理不严谨,或表达哕嗦的现象.若改成“三角形的三边a,b,c如果长度满足a~2+b~2=c~2,那么边a,b的夹角是直角.”结果就会更精彩.下面,笔者举例予以说明.
Beijing Normal University Edition 8 mathematics textbook volume (July 2013 1st edition) “Pythagorean theorem inverse theorem ” is expressed as: “If the triangle on both sides of a, b, c satisfy a ~ 2 + b ~ 2 = c ~ 2, then this triangle is a right triangle. ”This statement is true, but in the use of reason there is often not reasoning rigor, or the expression of wordy phenomenon .If the“ triangular ”a , b, c If the length satisfies a ~ 2 + b ~ 2 = c ~ 2, then the angle between the sides a, b is a right angle. "The result will be more exciting.