Search found 138 matches
- Mon Jan 28, 2013 3:42 pm
- Forum: Social Lounge
- Topic: May We Post Regional Problems?
- Replies: 2
- Views: 5264
May We Post Regional Problems?
All Regional Math Olympiads have been ended now. May we post the problems ?
- Mon Jan 28, 2013 1:02 pm
- Forum: Social Lounge
- Topic: Negative Marking
- Replies: 7
- Views: 5909
Re: Negative Marking
@nafistiham. Good explaination. I agree on your point.
- Mon Jan 28, 2013 12:48 pm
- Forum: Combinatorics
- Topic: Rubik's Cube Comb
- Replies: 4
- Views: 4648
Re: Rubik's Cube Comb
I'm saying what I did. The centers are fixed. Excluding centers there 20 small cubes outside. 8 of them are in the corners and 12 in middles. 12 middles can be arranged in 12! ways and as each middles has two colors, permutation for middles = $12!\times 2$ 8 corners can be arranged in 8! ways and ea...
- Sun Jan 27, 2013 10:32 pm
- Forum: Combinatorics
- Topic: Rubik's Cube Comb
- Replies: 4
- Views: 4648
Rubik's Cube Comb
A $3 \times 3$ Rubik's cube has different colors on its each sides.
In how many different ways the cube can be arranged ?
In how many different ways the cube can be arranged ?
- Sun Jan 27, 2013 3:54 pm
- Forum: Social Lounge
- Topic: Negative Marking
- Replies: 7
- Views: 5909
Negative Marking
Is there any negative marking for giving wrong answer in divisional olympiads ?
Somebody know??
Somebody know??
- Sun Jan 27, 2013 1:06 am
- Forum: Junior Level
- Topic: 2007 National, Junior 11
- Replies: 2
- Views: 9926
2007 National, Junior 11
If $a,b,c$ are the sides of a triangle such that $a^2+b^2+c^2=ab+bc+ca$. Prove that the triangle is equilateral.
- Sun Jan 27, 2013 12:55 am
- Forum: Divisional Math Olympiad
- Topic: Some problems of last year divisionals, I need help for
- Replies: 36
- Views: 20499
Re: Some problems of last year divisionals, I need help for
1st digit(rightmost) has 5 values. For other digits the cases are: Case 1: 2nd & 3rd digit are even and 4th is odd. All can have 5 values. $5 \times 5 \times 5 \times 5=625$ Case 2: 2nd even,3rd odd and 4th even. 4th digit has 4 values. $5 \times 5 \times 5 \times 4=500$ Case 3: 2nd odd,3rd even and...
- Thu Jan 24, 2013 6:01 pm
- Forum: Physics
- Topic: will it come back
- Replies: 9
- Views: 7407
Re: will it come back
Remember gravity doesn't depend on ball's mass, it depends on its place.
If you throw it outside the earth's gravity, then it will not come back. But if there is gravity, then it will.
If you throw it outside the earth's gravity, then it will not come back. But if there is gravity, then it will.
- Thu Jan 24, 2013 5:42 pm
- Forum: Number Theory
- Topic: minimum please!
- Replies: 8
- Views: 5748
Re: minimum please!
I think you're talking about this sequence
$2,4,8,16.....,2^n$
$2^n$ has $(n+1)$ factors.
$2,4,8,16.....,2^n$
$2^n$ has $(n+1)$ factors.
- Fri Jan 18, 2013 12:45 pm
- Forum: Junior Level
- Topic: Ratio of the sides
- Replies: 2
- Views: 2854
Re: Ratio of the sides
I did:
Let $AB=a$ & $BC=b$
$OA = \frac {\sqrt {a^2+b^2}}{2}$
In $\triangle AOM, Cos A = \frac {OA}{\frac{2a}{3}}$
In $\triangle ABC, Cos A = \frac {a}{2OA}$
Solving them we will get $\frac {a}{b} = \sqrt 3$
Let $AB=a$ & $BC=b$
$OA = \frac {\sqrt {a^2+b^2}}{2}$
In $\triangle AOM, Cos A = \frac {OA}{\frac{2a}{3}}$
In $\triangle ABC, Cos A = \frac {a}{2OA}$
Solving them we will get $\frac {a}{b} = \sqrt 3$