Jawabanmu

2014-04-14T19:27:45+07:00
0,643+0,342+(-0,985) = 0
Karena tidak sudut istimewa jadi pakai kalkulator

semoga membantu:)
2014-04-14T20:07:10+07:00
(cos 50'+cos70')+cos170'
=2cos60'cos-10'+cos170'
=1cos10+cos170'
=2cos90.cos-80
=0