资中县2018年下期八年级数学第二次自测试题参考答案及评分意见

1、资中县 2018-2019 学年度第一学期第二次自测八年级数学参考答案及评分意见124481C2B3C4A5D6D7B8D9A10B11A12C(4416136x2y3141151611027(656 )17.1( 3)21 93 (27 )(2) 216643532424142(2x y)(3x2y) 2y( y 3x)6x24xy3xy2 y22 y 26xy26x 2xy433x3 12x2 y 12xy23x( x 24xy 4y 2 )23x( x2y) 2 .418EAB= CAD ,EAB+ EAC= CAD+ EAC,BAC= DAE .2BACDAEABAD ,BACDAE

2、,ACAE,BACDAE.5C= E.719.1ABDBCEACDBAE.2ABDBCEABCAB=BCABC= C=60 .3八年级数学第2 次自测答案第 1 页（共 4 页）ABDBCEABBC, ABCC,BDCE,ABDBCE.5ACDBAE2APB.6ABDBCE ，BADCBE.7BAD+ ABP= CBE+ ABP= ABC =60 .8BAD+ ABP+ APB=180 APB=120 .APB.920. 1DMENACBCAM =CM, BN=CN.2CMN15cmCM+MN +CN=15cm,AM +MN+BN=15cm,AB=15cm.42DMENACBCFDC = FE

3、C =90 .5FDC + FEC + MFN + ACB=360 MFN =70,ACB=110.6ACB+ A+ B=180 A+ B=70.7AM=CM, BN=CN,ACM= A, BCN= B.ACM+ BCN= A+ B= 70.8ACM+ BCN+ MCN= ACB=110 MCN=40.921.1x30a x20b( x30)( x 20)ab10 ab( x 30) ( x 20)10 .2( x 30) 2 (x 20) 2 a 2 b2 (a b) 2 2ab ( 10) 2 2 10 120 .42x 2017a x2019b( x 2017) 2(x2019)2a 2

4、b24042 a b ( x2017) ( x 2019)2 .6( x 2017)( x2019)ab1( a 2b 2 ) ( a b) 2 1( 4042 22 )2019 .228八年级数学第2 次自测答案第 2 页（共 4 页）22.1t=1AP =1 BQ=2 BP=AB- AP=8-1=7.1ABC=90,PQBP2BQ 27 22253 (cm).32ABC=90 AB=8cm BC= 6cmACAB 2BC 2826210 (cm).4ABCAB +BC +AC=8+6+10=24(cm).PQABC2t 8 t1t4 .242.PQABCt4.63QCACQ( 2t6)cm .BCQCQ=BCCQ=BQBC=BQ.CQ=BC12t6 6t6 .7CQ=BQ2C= CBQ.ABC=90,CBQ+ABQ=90,C+A=90.ABQ=A.BQ=AQ.CQ=AQ= 1 AC1105 (cm).22112t 695t.2BC=BQB BE ACE31AC BE111018 6 .S ABCABBCBE224222BE.5CEBC 2BE262(24)218.55BC=BQ BE ACQE18.CQCE QE36CE.552t636