Dhaka Secondary 2010/10

Problem for Secondary Group from Divisional Mathematical Olympiad will be solved here.
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BdMO
Posts: 134
Joined: Tue Jan 18, 2011 1:31 pm

Dhaka Secondary 2010/10

Unread post by BdMO » Fri Jan 21, 2011 7:07 pm

Three points are taken on each of any three sides of a square. What is the total number of points taken on the other side given that a total of $45$ distinct straight lines can be drawn using these points?

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leonardo shawon
Posts: 169
Joined: Sat Jan 01, 2011 4:59 pm
Location: Dhaka

Re: Dhaka Secondary 2010/10

Unread post by leonardo shawon » Sat Jan 29, 2011 11:27 pm

we need TWO Points to make a straight line. Given 3 points will make 3 lines. $(45-2)=42$ lines need 84 points. 3 points are given. So we need 81 more points to create straight lines among themselves.

.............????
Ibtehaz Shawon
BRAC University.

long way to go .....

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