Question

【題目】如圖，中，，把繞著點(diǎn)逆時(shí)針旋轉(zhuǎn)，得到，點(diǎn)在上.

（1）若，求得度數(shù)；

（2）若，，求中邊上的高.

Answer 1

【答案】（1）∠BAC =50°；（2）

【解析】

解：(1) 由旋轉(zhuǎn)得△ACB≌△DEB

∴BD = BA

∴∠BAD =∠BDA=

∴∠ABD=

∴∠ABC =∠ABD=

∵∠C=

∴∠BAC=·········································································· 5分

(2) ∵BC = 8，AC= 6，∠C=

∴

∵∠DEB =∠C=且BE=BC= 8，DE ="AC" = 6

∴AE =" AB" – BE = 2

在Rt△DEA中，

設(shè)AD邊上的高為h

∴

∴······················································· 10分