论文部分内容阅读
一、出现问题在一次练习中有这样一道再普通不过的题目,但是却引起了老师之间的争论,争论的主要问题是解题的格式问题,主要是在解题的因果关系上面有一定的分歧.例1如图1,在ΔABC中,∠C=90°,AC=8 cm,BC=6 cm.一动点P从B点出发,沿BC的方向向C点移动,速度为每秒1 cm,另一个动点Q从C点出发,沿CA的方向向A点移动,速度为每秒2 cm,问:当P,Q同时开始运动后几秒钟,ΔCPQ～ΔCAB?有的同学是这样来解答的:解设x秒后,△CPQ～△CAB,当ΔCPQ～ΔCAB时,CP:CA=CQ:CB,又因为BP=x cm,CP=(6
First, there is a problem There is such an ordinary topic in an exercise, but it arouses controversy among teachers. The main problem in the debate is the format of the problem-solving, mainly in the causal relationship of the problem-solving Example 1 As in Figure 1, ΔC = 90 °, AC = 8 cm, BC = 6 cm in ΔABC. A moving point P moves from point B to point C in the direction of BC at a rate of 1 per second cm, and the other moving point Q starts from point C and moves along the direction of CA to point A at a speed of 2 cm per second. Q: A few seconds after P and Q start to exercise at the same time, some students of ΔCPQ ~ ΔCAB? To solve this problem: After solving x seconds, ΔCPQ ~ △ CAB, when ΔCPQ ~ ΔCAB, CP: CA = CQ: CB, and because BP = xcm, CP =