2011-2012

(12560)D2{an}nSn.a111a4a66Snn ()A6 B7C8 D9AD

5()A. B. C. D.BCC

6ABCABCabc(a2c2b2)tan BacB ()A. B.

C. D. D7{an} a1a2a3 5a7a8a910a4a5a6 ()A5 B7C6 D4A8xy zx2y ()A4 B3 C2 D1B

10{an}20100a3a18 ()A50 B25C100 D2BAD

12ABC ABCabcC120c ()Aab B.abCab DabA(4520)D

13.14_________;

14ABCa4b6C120sin A________15 _________. 16 xRa_(____)_