1. 已知BD是等腰三角形ABC上的高，且∠ABD=50°，求△ABC的三內角的度數。
2.△ ABC內部有一點P，使∠PAB=10°，∠PBA=20°，∠PCA=30°，∠PAC=40°，求證△ABC是等腰三角形。
數學知識交流(13)
2011-03-23 4:36 am
回答 (2)
2011-03-23 7:28 am
✔ 最佳答案
(1) ABC是那兩條等腰?2011-03-22 23:28:56 補充：
http://i1090.photobucket.com/albums/i376/Nelson_Yu/1-144.jpg
圖片參考：http://i1090.photobucket.com/albums/i376/Nelson_Yu/1-144.jpg
2011-03-23 21:24:15 補充：
The 4 cases are as shown:
http://i1090.photobucket.com/albums/i376/Nelson_Yu/1-148.jpg
The possible angles are A,B, C
(1) 40,70,70
(2) 40,100,40
(3) 40,40,100
(4) 140,20,20
2011-03-23 6:03 am
..........B ^
............/..\
.........../..^.\
........../50"D\
........./....|....\
......../.....|.....\
......./......| .....\
....../ ..............\
...../.................\
..../...................\
.../.........Y..........\
A --------------------C
angle ABD=50and times two=angle ABC(have to find out the angle of ABC)
in form 2 we know that if is a等腰三角形下2隻ANGLE係一樣.小4你知3個angle加埋係180渡
知道係(180-<50X2>)over 2=ANSWER
80/2=40<我唔知你英中定中中.@@
第2個圖"
PAB=10
PBA=20
PCA=30
PAC=40
DIVIDE it into three traingle
p is a circle and have 360 "o
peter)180-pab-pba=180-10-20=150
apple)180-pac-pca=180-30-40=110
360-peter-apple=110
so we can know-PCB/PBC=50/20
hope i can help you^^"
............/..\
.........../..^.\
........../50"D\
........./....|....\
......../.....|.....\
......./......| .....\
....../ ..............\
...../.................\
..../...................\
.../.........Y..........\
A --------------------C
angle ABD=50and times two=angle ABC(have to find out the angle of ABC)
in form 2 we know that if is a等腰三角形下2隻ANGLE係一樣.小4你知3個angle加埋係180渡
知道係(180-<50X2>)over 2=ANSWER
80/2=40<我唔知你英中定中中.@@
第2個圖"
PAB=10
PBA=20
PCA=30
PAC=40
DIVIDE it into three traingle
p is a circle and have 360 "o
peter)180-pab-pba=180-10-20=150
apple)180-pac-pca=180-30-40=110
360-peter-apple=110
so we can know-PCB/PBC=50/20
hope i can help you^^"
收錄日期: 2021-04-13 17:53:24
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110322000051KK01105