figure: http://img823.imageshack.us/img823/3237/69194653.jpg
In the figure, A, B, C and D are points lying on the circle. If AB = 5, AD = 3 and BD = 7, then angle BCD =
A. 60
B. 85
C. 95
D. 120
F5 Maths
2010-09-27 1:59 am
回答 (2)
2010-09-27 2:24 am
✔ 最佳答案
Cos A = (5^2 + 3^2 - 7^2) / [(2)(5)(3)]Cos A = - 1/2
A = 120°
A + C = 180° (圓內接4邊形對角互補)
120° + C = 180°
C = 60°
Answer : (A)
2010-09-27 2:14 am
但我計到96既?!
咁C囉
咁C囉
收錄日期: 2021-04-21 22:18:02
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100926000051KK01379