为对称轴画△CBD′对称于△CBD(2)找到AC的中点D画DE‖CB并让EB⊥CB
则画出了矩形DCBE八、(1)过N点做NH‖BC交AE于G则∠MHN=∠C=90°=∠B
∠NGO+∠ONG=90°∠NAO+∠OGN=90°∴∠NGO=∠NAO又∵∠MHN=∠BNH=BC=AB
∴△ABE≌△MNH∴AE=MN=10㎝(2)解:∵∠A=40°AB=AC∴∠ABC+∠C=140°
∠ABC=∠C=70°∵AE=EB∠AED=∠BEDED=ED∴△AED≌△BED
∠EBD=∠A=40°∠DBC=70°—40°=30°∠BDC=180°—70°—30°=80°
70°≠30°≠80°既BC≠DC≠BD∴△BCD不是等腰三角形
英语37页答案:
公共英语标志:
勿折花木
handsofftheflowersandtrees
来宾登记
visitorspleaseregister
请勿践踏草坪
Pleasekeepoffthegrass
请随手关门
Pleaseshutthedoorafteryou
勿乱扔废弃物
Nolittering
38页答案
英语谚语
第一题1不入虎穴焉得虎子2人善被人欺,马善被人骑3耳朵发烧有人念叨4杀鸡取卵
第2题改为条件状语从句
得寸进尺:ifyougivehiminch,hewilltakeamile
早睡早起,精神百倍:ifamangoestobedearlyandwiseearly,hewillbehealthywealthy,andwise
自助者天自助:ifyouhelpyourselfs,godwillhelpyou
自己不动,叫天何用:ifamanwhodoesn'tactheavenwillneverhelphim
不劳无获:iftherearenopain,therewillbenogain
第3题积累谚语
Abadbeginningmakesabadending.
恶其始者必恶其终。