|
|
|
|
|
| Author |
Message |
![[Post New]](/templates/default/images/icon_minipost_new.gif) 22 Mar 2008 19:24:23 IST
|
|
|
1)
a=120,d=5
Sn=(n-2)180
Sn=n/2(2a+(n-1)d)
=n/2(240+(n-1)5)
180n-360=n/2(235+5n)
360n-720=235n+5n*n
n2-25n+144=0
or n=9 or 16
thanks to nadeemoidu...
n=16 has to be omitted since angle>180
so n=9 is the only solution
|
" Always remember money isn't everything but make sure you have made a lot of it before talking such nonsense!"
- Bill Gates |
this reply: 4 points
(with 0 
in 2 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
|
|
|
|
|
|
|
Moderation Team
![[Up]](/templates/default/images/icon_up.gif "[Up]"){kind=icon}
