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**RauLiTo****Member**- From: Bahrain
- Registered: 2006-01-11
- Posts: 142

get the value of :

sin 75 + sin 25

ImPo$$!BLe = NoTH!nG

Go DowN DeeP iNTo aNyTHinG U WiLL FinD MaTHeMaTiCs ...

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**RauLiTo****Member**- From: Bahrain
- Registered: 2006-01-11
- Posts: 142

i got sin 75 but the problem with sin 25

sin 75 = sin ( 45 + 30 ) = sin 45 cos 30 + cos 45 sin 30 = ( √ 3 + 1 ) / ( 2 √ 2 )

ImPo$$!BLe = NoTH!nG

Go DowN DeeP iNTo aNyTHinG U WiLL FinD MaTHeMaTiCs ...

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**RauLiTo****Member**- From: Bahrain
- Registered: 2006-01-11
- Posts: 142

guys ?!

ImPo$$!BLe = NoTH!nG

Go DowN DeeP iNTo aNyTHinG U WiLL FinD MaTHeMaTiCs ...

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**luca-deltodesco****Member**- Registered: 2006-05-05
- Posts: 1,470

i tried but i cant think of anyway of getting sin 25

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The End Of All Things To Come.

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**RauLiTo****Member**- From: Bahrain
- Registered: 2006-01-11
- Posts: 142

oooh thanks alot luca .... anybody else ?

ImPo$$!BLe = NoTH!nG

Go DowN DeeP iNTo aNyTHinG U WiLL FinD MaTHeMaTiCs ...

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**luca-deltodesco****Member**- Registered: 2006-05-05
- Posts: 1,470

lol i was about to answer for sin 75, but just after i posted it, you had posted yours, so i just deleted it

The Beginning Of All Things To End.

The End Of All Things To Come.

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**RauLiTo****Member**- From: Bahrain
- Registered: 2006-01-11
- Posts: 142

heheheh ooh

we want the sin 25 now or maybe there is a different way

ImPo$$!BLe = NoTH!nG

Go DowN DeeP iNTo aNyTHinG U WiLL FinD MaTHeMaTiCs ...

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**Toast****Real Member**- Registered: 2006-10-08
- Posts: 1,321

I wikipedia-ed exact trigonometric constants and it said:

Wikipedia wrote:

All values of sine, cosine, and tangent of angles with 3° increments are derivable using identities: Half-angle, Double-angle, Addition/subtraction and values for 0°, 30°, 36° and 45°. Note that 1° = π/180 radians.

As 25 degrees is not divisible by 3, I would presume that there is no exact value for it. Although I must say, I'm not an expert in this area.

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**Stanley_Marsh****Member**- Registered: 2006-12-13
- Posts: 345

25x3=75

Sin3a= 3sina - 4(sina^3) after simplification(don't know if I am correct) , then just solve the equation.but how to solve it? lol.

Numbers are the essence of the Universe

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**RauLiTo****Member**- From: Bahrain
- Registered: 2006-01-11
- Posts: 142

thats the question

i know the rule for

sin / cos 3 θ but i dont know how to use it !

ImPo$$!BLe = NoTH!nG

Go DowN DeeP iNTo aNyTHinG U WiLL FinD MaTHeMaTiCs ...

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