更新1:
Can 002 please show the steps, thanks. Without this, it is difficult to offer you the points. Please help.
Quadrilateral
2009-04-24 7:21 pm
OABC is a quadrilateral (O is the origin and counting anti-clockwise). AB = 15, BC = 9 and OC = 10. Angle COA = 80 degree, angle OAB = 30 degree. Find length of OA and angle ABC. (correct to 3 sig. fig.)
回答 (3)
2009-04-25 9:27 am
✔ 最佳答案
The answer is as follows:圖片參考：http://i320.photobucket.com/albums/nn347/old-master/090425_1.jpg?t=1240594005
2009-04-24 9:21 pm
OA = 23.4 (correct to 3 sig. fig.)
angle ABC = 165 degree (correct to 3 sig. fig.)
angle ABC = 165 degree (correct to 3 sig. fig.)
2009-04-24 8:09 pm
since OABC is a quadrilateral and O is the origin
then OA = OC = radius = 10
let E be a point on the arc AC
angle AEC = 1/2 angle COA =40 degree
(angle at center=2 angle at circumference)
angle AEC + angle ABC = 180 degree (圓內接四邊形對角互補)
angle ABC= 180-40 =140 degree
then OA = OC = radius = 10
let E be a point on the arc AC
angle AEC = 1/2 angle COA =40 degree
(angle at center=2 angle at circumference)
angle AEC + angle ABC = 180 degree (圓內接四邊形對角互補)
angle ABC= 180-40 =140 degree
收錄日期: 2021-04-29 18:17:08
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20090424000051KK00374