文档介绍:八年级第二章《特殊三角形》
一、选择题(每小题3分,共27分)
°,那么一个底角的度数为···················( )
A.35° B.55° C.65° D.110°
,对称轴最多的是············································( )
A.等腰三角形 B.等边三角形 C.直角三角形 D.等腰直角三角形
3.判断结论:①等边三角形是轴对称图形;②等边三角形是中心对称图形,结果是···( )
A.①②都正确 B.①②都错误 C.①正确,②错误 D.①错误,②正确
4.△ABC中,∠A:∠B:∠C=4:5:9,则△ABC是····························( )
,且∠A=90° ,且∠B=90°
,且∠C=90°
,不能组成直角三角形的是······························( )
,4,5 ,12,13 ,8,10 ,5,6
,在Rt△ABC中,CD是斜边AB上的中线,则图中与CD相等的线段有·····( ) 、BD与BC
B
D
C
A
(第6题) (第7题)
,△ABC中,∠C=90°,AB的中垂线DE交AB于E,交BC于D,若AB=10,AC=6,
则△ACD的周长为······················································( )
A.16
,△ABC中,AB=AC=6,BC=8,AD平分∠BAC交BC于点D,DE//AC交AB于点E,则△BDE的周长为··············································( )
A. B. C.10 D.12
(第8题) (第9题)
,△ABC中,∠ACB=90°,D在BC上,E为AB之中点,AD、CE相交于F,且AD=∠B=20°,则∠DFE等于············································( )
A.30° B.40° C.50° D.60°
二、填空题(每小题4分,共20分)
°.
°,则较大的锐角的度数为 °
△ABC中,∠C=90°∠B