## Search found 35 matches

Thu Jan 17, 2013 3:31 pm
Forum: Combinatorics
Topic: Sobhan's Toothpick Sum
Replies: 1
Views: 1558

### Sobhan's Toothpick Sum

Sobhan has two toothpicks each with the same length. He accidentally drops the toothpicks to the floor and each one breaks into two pieces. The probability that the two largest pieces are each larger than the sum of the lengths of the the two smallest pieces can be expressed as a/b where a and b are...
Thu Jan 17, 2013 11:44 am
Topic: Some problems of last year divisionals, I need help for
Replies: 36
Views: 10415

### Re: Some problems of last year divisionals, I need help for

Hehehe..
Thu Jan 17, 2013 10:38 am
Topic: Some problems of last year divisionals, I need help for
Replies: 36
Views: 10415

Assuming That $F$ is the midpoint. If We draw the circumcircle of $\triangle ABC$, $AC$ and $DE$ will be the Diameter of the circle. As $FE$ is perpendicular to $BC$, $\widehat {BE} = \widehat {EC} = \frac {\widehat {BC}}{2}$ . so, $\angle BAC=2 \cdot \angle BDE$. $\frac {(AB \sin \angle BAC)}{(BD \... Thu Jan 17, 2013 10:09 am Forum: Divisional Math Olympiad Topic: Some problems of last year divisionals, I need help for Replies: 36 Views: 10415 ### Re: Some problems of last year divisionals, I need hel for More problems have arrived............ Dhaka Secondary 2012$10.$In the given diagram, both$ABC$and$DBE$are right triangles,$B$being the right angle for both. They have hypotenuses of same length.$DE$is perpendicular on$BC$. Area of$ABC$is$\sqrt 3$times of$DEF$. Find$\angle BDE\$. Is...
Sun Dec 09, 2012 10:56 pm
Forum: Introductions
Topic: Participation in math olympiad 2013
Replies: 19
Views: 8344

### Re: Participation in math olympiad 2013

You can find the solutions in the Olympiad Category. The weekly discussion is held in Ramanujan Math Club every Friday . Here is the facebook link of the group http://www.facebook.com/groups/rgs314/?fref=ts . You will find the details there. You should not get frustrated . Mahi got selected the firs...
Sun Dec 09, 2012 11:48 am
Forum: Introductions
Topic: Participation in math olympiad 2013
Replies: 19
Views: 8344

### Re: Participation in math olympiad 2013

I thought ' Art and Craft' is the easy one. And It is appropriate for the beginners .
Wed Sep 05, 2012 5:41 pm
Forum: Combinatorics
Topic: korea 2009(3)
Replies: 0
Views: 1104

### korea 2009(3)

2008 white stones and 1 black stone are in a row. An 'action' means the following: select one black stone and change the color of neighboring stone(s).
Find all possible initial position of the black stone, to make all stones black by finite actions.
Tue Jan 10, 2012 10:55 pm
Topic: BdMO 2004 Secondary - 2(b)
Replies: 4
Views: 3003

### Re: BdMO 2004 Secondary - 2(b)

my mistake. my answer is also $\pm$ $x=\sqrt2$
Mon Jan 09, 2012 10:13 pm
Topic: BdMO 2004 Secondary - 2(b)
Replies: 4
Views: 3003

### Re: BdMO 2004 Secondary - 2(b)

I can't write latex well. so I am giving short solution with banglish.( can't know the english of some word)
bracket ar vitorer ongshe osim gunnottor dharar sutro proyog korle :
3(X^2+2X) = 2(1+2X+X^2)
and ata solve korle
X = -(1+root3) or root3 -1 answer ase
If i haven't done any mistake
Mon Jan 02, 2012 6:39 pm