25.3 相似三角形 预学检验+课堂导学（含答案）2024-2025学年冀教版数学九年级上册

第二十五章　图形的相似 25. 3 相似三角形 INCLUDEPICTURE"复习回顾.tif" INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\复习回顾.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\复习回顾.tif" \* MERGEFORMATINET 1．如图，△ABC≌△DEF，点A与D，点B与E分别是对应顶点，且测得BC＝5 cm，BF＝7 cm，则EC的长为_____cm. INCLUDEPICTURE"image3100.tif" INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\image3100.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\image3100.tif" \* MERGEFORMATINET 2．如图，在△ABC中，在边BC上取一点D，连接AD，在AD上取一点E，连接CE.若△ADB≌△CDE，∠BAD＝α，则∠ACE的度数为_____． INCLUDEPICTURE"image3101.tif" INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\image3101.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\image3101.tif" \* MERGEFORMATINET INCLUDEPICTURE"预习效果检测.tif" INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\预习效果检测.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\预习效果检测.tif" \* MERGEFORMATINET 1．对应角_____、对应边_____的两个三角形叫做相似三角形．相似三角形对应边的比叫做它们的_____． 2．三角形全等是三角形相似的特殊情况，全等三角形可以看成是相似比为_____的相似三角形． 3．平行于三角形一边的直线和其他两边(或它们的延长线)相交，所截得的三角形与原三角形_____． 4．已知△ABC∽△A′B′C′，且相似比为2，则(　　) A．∠A是∠A′的2倍 B．∠A′是∠A的2倍 C．AB是A′B′的2倍 D．A′B′是AB的2倍 5．[2023福州鼓楼区模拟如图，△ABC∽△ADE，若∠A＝60°，∠ABC＝45°，则∠E＝(　　) A．75° B．105° C．60° D．45° INCLUDEPICTURE"image3102.tif" INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\image3102.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\image3102.tif" \* MERGEFORMATINET (第5题)　　　　　INCLUDEPICTURE"image3103.tif" INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\image3103.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\image3103.tif" \* MERGEFORMATINET (第6题) 6．[2023成都双流区期末]如图，△ABC∽△CBD，AB＝4，BD＝6，则BC＝_____． INCLUDEPICTURE"课堂导学.tif" INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\课堂导学.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\课堂导学.tif" \* MERGEFORMATINET INCLUDEPICTURE"W21.tif" INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\W21.tif" \* MERGEFORMATINET 知识点1 相似三角形的概念及其相似比INCLUDEPICTURE"L1.tif" INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\L1.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\L1.tif" \* MERGEFORMATINET 如图所示，已知△AOB∽△DOC，OA＝2，AD＝9，OB＝5，DC＝12，∠A＝108°，求AB，OC的长和∠D的度数． INCLUDEPICTURE"image3104.tif" INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\image3104.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\image3104.tif" \* MERGEFORMATINET 变式1如图，D是AB的中点，△ABC∽△ACD，且AD＝2，∠ADC＝65°. (1)写出△ABC与△ACD的对应边成比例的比例式； (2)求AC的值及∠ACB的度数． INCLUDEPICTURE"image3105.tif" INCLUDEPICTURE "D:\\课件\\九数JJ河北（北京）\\image3105.tif" \ ... ...