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Trignometry

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5 Apr 2007 11:59:49 IST

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1225

bonus before JEE !!!!!!!!!!!!!!!!

None

........................Sin 18 degree

sin2# = sin3# (below 18 degrees)

..............if there is

acos# + b sin# = c

then -

a² + b² <- c <

a² + b²

^{...................}

^{i the type of qs.....}

sin^ax + sinbx = summation n=0 to n c_ncosmx

then the vaule of n is

highest value of a + coeff. of x in sin x

eg. sin³x + sin3x = summation n=0 to n c_ncosmx

then value of n is sin³x +sin3x

n = 3 + 3 = 6

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Comments (13)

Himanshu

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5 Apr 2007 12:03:17 IST

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sinpi / 14*sin3pi/14*sin5pi/14 *sin7pi/14 *sin9pi/14
its ans is 1 / 2^n-1
n = no. of terms
(condition .. 1 sin term must b standardised eg. in above case sin7pi/14 can b written as sinpi/2)
(denominator must b even)

anshul sharma

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5 Apr 2007 15:32:35 IST

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good................

Himanshu

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5 Apr 2007 21:50:50 IST

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thanx

Himanshu

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5 Apr 2007 22:01:38 IST

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value of
sin pi / 7 + sin 2 pi / 7 + sin 3pi / 7 = ?
shortcut

= 1/2 cot(1/2*first angle)
here

= 1/2 cot(1/2.pi/7)

Himanshu

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5 Apr 2007 22:05:07 IST

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sin pi / 7 *sin 2 pi / 7 * sin 3pi / 7
(note --- here denominator is odd in above sin cases den was even)

= (denominator)^1/2 / 2^n
n = no. of terms
here
= (7)^1/2 / 2^3
= sq. root 7 / 8

Nitesh Nakli

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5 Apr 2007 22:12:41 IST

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great yaar

Himanshu

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5 Apr 2007 23:04:07 IST

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thank u..........................

anshul sharma

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6 Apr 2007 12:27:09 IST

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yup
great

Himanshu

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6 Apr 2007 21:17:28 IST

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thanxxxxx

vir sharma

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6 Apr 2007 22:53:43 IST

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great yaar

Himanshu

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7 Apr 2007 11:12:29 IST

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thank u
thank u all

Avinash Bhat

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8 Apr 2007 20:42:45 IST

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Great !! Take a rate...

Himanshu

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8 Apr 2007 22:59:58 IST

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thanx .......

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