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  Discussion about math, puzzles, games and fun.   Useful symbols: √ ∞ ≠ ≤ ≥ ≈ ⇒ ∈ Δ θ ∴ ∑ ∫ π -

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Topic review (newest first)

niharika_kumar
2014-03-10 19:06:56

wow, that's really great.

thanks for your suggestion.will try that after my exams are over. smile

ShivamS
2014-03-10 03:08:26

niharika_kumar wrote:

JEE is my goal and its preparations are going in parallel,  but now I am in class10 so my focus is more on boards.
Did you give JEE,if yes then how was it?

Just saw this post right now...
It wasn't extremely hard. I managed to crack the main and the advanced (AIR 52) but decided to go to MIT instead. For your preparation, try plancess.com (it gives tutorials by IIT JEE crackers AIR <100). Use NCERT books for all the subjects, but for physics go for HC Verma.
Good luck.

niharika_kumar
2013-11-21 15:33:19

yes (as far as I know).

Agnishom
2013-11-21 04:16:54

What is JEE? Joint Entrance Examinations?

niharika_kumar
2013-11-21 03:59:23

JEE is my goal and its preparations are going in parallel,  but now I am in class10 so my focus is more on boards.
Did you give JEE,if yes then how was it?

ShivamS
2013-11-20 08:13:56

Niharika, you are preparing for the JEE?

niharika_kumar
2013-11-19 15:29:24

thank you! smile

bob bundy
2013-11-17 10:44:06

hi niharika_kumar

When the ray hits mirror B for the first time it has travelled in the right/left direction



This can happen until it has travelled 2root 3 in that direction.  Say it happens n times then





But the ray has also hit A at the start so add one, but 'just' misses B at the end so take one off.

Hence the maximum number of reflections is 30.

Bob

Nehushtan
2013-11-17 07:44:50

I got 35 instead but I dont know where I went wrong. sad

EDIT: I got it now. I carelessly used sin instead of tan.

ShivamS
2013-11-17 05:26:36

What a coincidence! This is the same question I encountered while taking the IIT JEE some years back. The answer is 30.

bobbym
2013-11-17 05:13:36

Hi;

The formula says 30.

Agnishom
2013-11-17 03:36:14

http://www.mathisfunforum.com/showimage.php?pid=290049&amp;filename=mirror.gif

bobbym
2013-11-17 03:30:59

It is in post reply on the bottom, I can make a picture of it if you need it.

niharika_kumar
2013-11-17 03:29:25

i am still not able to find the upload option in this section.

niharika_kumar
2013-11-17 03:28:14

pls copy paste the following link for the fig.:-

http://www.mathisfunforum.com/viewtopic.php?pid=290049#p290049

post #77

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