F4 Maths ( 20 mark)

As follows:

圖片參考：http://i707.photobucket.com/albums/ww74/stevieg90/01-98.jpg


2010-05-21 17:50:21 補充：
http://i707.photobucket.com/albums/ww74/stevieg90/01-98.jpg

2010-05-22 20:31:33 補充：
Should be -1.

1) cos^2 10+cos^2 20+cos^2 30+...+cos^2 170
= cos^2 10 + cos^2 20 + cos^2 30 + ... + cos^2 (180-20) + cos^2 (180-10)
= cos^2 10 + cos^2 20 + cos^2 30 + ... + cos^2 80 +cos^2 90 + sin^2 80 + ... + sin^2 20 + sin^2 10
= 8*1 + 0
= 8

2010-05-21 15:05:34 補充：
2) tan95tan105tan115...tan175
= tan95tan105tan115...tan(270-95)
= 1

2010-05-21 15:32:48 補充：
tan95tan105tan115...tan(270-95)
= tan95tan105tan115/tan95tan115tan105
= 1
I have not used calculator

2010-05-22 15:05:51 補充：
tan95tan105tan115.../...tan95tan115tan105
= (-tan5)(-tan15).../(-tan5)(-tan15)...
= 1 , which is positive