题干

我们在学习三角形相似时,往往是添加平行线构造相似三角形的基本图形.有一学生根据这一理论猜想三角形内角平分线有这样一个性质:如图,在△ABC中,AD平分∠BAC,则
B
D
C
D
=
A
B
A
C
.如果你认为这个猜想是正确的,请写出一个完整的推理过程.
 
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答案(点此获取答案解析)

证明:过点D作DE∥AB交CA于点E,

∵DE∥AB,

∴∠EDA=∠BAD,

∵AD平分∠BAC,

∴∠BAD=∠EAD,

∴∠EDA=∠EAD,

∴EA=ED,

∵DE∥AB,

∴CDBD

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                                                                                     Guided Walking Week April 2016

          Dates: April 30th-May 7th 2016

          Location: Abdet, Costa Blanca

         A week of guided walking in the mountains around Abdet. Highlights include the climbing of Valencia's highest summit (Sierra de Aitana), traveling completely around the impressive Puig Campana, and several explorations in the Sierra de Aitana. Ancient trails lead through spectacular canyons(峡谷) to abandoned settlements situated high in the mountains. You will discover the snow trader routes which lead from the incredible snow holes high in the mountains down to the villages and towns on the coast. These years, golden eagles have made a return to this area, and you may also see other animals—wild goats, foxes, wild pigs and red squirrels.

         As part of the week you are invited to help clear some local walking paths. This involves clearing collapsed walls and rocks, cutting back fallen trees. This is of course optional and is just for half a day, it's actually great fun!

Price:$499

Includes:

  Accommodation in the beautiful mountain village of Abdet

  All food-good home cooking

  Beer, wine, soft drinks

  Snacks and post walk treats

  Packed lunches & drinks(except café/bar visits)

  Expert guiding

  Photos/Videos of your days in the mountains

  Airport pick-up/return $25 each way(fly to Alicante)

  Single room supplement $75

  To book or get further information, please contact info@abdet. com.