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Half angle identities
- Thread starter bnosam
- Start date
HallsofIvy
Elite Member
- Joined
- Jan 27, 2012
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Do you need a hint to tell you that 12= 3(2)(2)? Start with sine and cosine of \(\displaystyle \frac{\pi}{3}\) and use the half angle identities twice.
Last edited:
D
Deleted member 4993
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How do I solve
cos 13π/12 using half angle identities? Some hints?
I have no clue, the book I'm learning from is poor (I'm doing an independent study course and it really sucks)
Thanks
Since you do not have a clue, let's start with definition/formula.
Can you tell us - what is the half angle formula for cosine function?
Then apply the hint supplied by HOI (above) into that equation.
You need to read the rules of this forum. Please read the post titled "Read before Posting" at the following URL:
http://www.freemathhelp.com/forum/th...217#post322217
We can help - we only help after you have shown your work - or ask a specific question (not a statement like "Don't know any of these")
Please share your work with us indicating exactly where you are stuck - so that we may know where to begin to help you.
Since you do not have a clue, let's start with definition/formula.
Can you tell us - what is the half angle formula for cosine function?
Then apply the hint supplied by HOI (above) into that equation.
You need to read the rules of this forum. Please read the post titled "Read before Posting" at the following URL:
http://www.freemathhelp.com/forum/th...217#post322217
We can help - we only help after you have shown your work - or ask a specific question (not a statement like "Don't know any of these")
Please share your work with us indicating exactly where you are stuck - so that we may know where to begin to help you.
Well I know the half angle identity of cosine is:
cos (X/2) = sqrt( (1 + cos X)/2)
I don't really understand the hint he gave me. The unit circle was printed in my book with only the first quadrant in it with the title "Memorize this for the problems".
Since you do not have a clue, let's start with definition/formula.
Can you tell us - what is the half angle formula for cosine function?
Then apply the hint supplied by HOI (above) into that equation.
You need to read the rules of this forum. Please read the post titled "Read before Posting" at the following URL:
http://www.freemathhelp.com/forum/th...217#post322217
We can help - we only help after you have shown your work - or ask a specific question (not a statement like "Don't know any of these")
Please share your work with us indicating exactly where you are stuck - so that we may know where to begin to help you.
Well I know the half angle identity of cosine is:
cos (X/2) = sqrt( (1 + cos X)/2)
I don't really understand the hint he gave me, maybe I'm frustrated and my mind isn't working right now well, I'm not sure. The unit circle was printed in my book with only the first quadrant in it with the title "Memorize this for the problems".