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#1 2008-07-22 21:42:07
- helloying
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- Registered: 2008-02-16
- Posts: 4
help with trigonometry
Sin y =-5/13 Cos y = -4/5
both of them are in the same quadrant. Find, without the use of calculator, value of Sin 1/2 y 
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#2 2008-07-22 22:35:56
- JaneFairfax
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- Registered: 2007-02-23
- Posts: 6,868
Re: help with trigonometry
and are both negative, so y is in the third quadrant, i.e.
i.e.
is in the second quadrant, where sin is positive and cos is negative.Now use the relation
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