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anonymous
 one year ago
Medal and Fan, if someone really good at pre calc could help me :)
anonymous
 one year ago
Medal and Fan, if someone really good at pre calc could help me :)

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anonymous
 one year ago
Best ResponseYou've already chosen the best response.0derive this identity from the sum and difference formulas for cosine: sin a sin b= (1/2){cos(ab)cos(a+n)}

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Alright here's the thing i got 69/100 on this practice test and my teacher is letting me redo for half a credit per correct answer. can someone help explain this one to me please :)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0@iGreen could you please take a look at this

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0@Loser66 i can show you my work if that helps?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0alright it might take a second there's a table and in the left hand side there's calculations, and on the right side is the reasoning

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0cos(ab)cos(a+b) over 2 reason: To manipulate the right side

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0ok then 2 sin (a+b)+a+b over 2) ^2 (a+a+bb over 2)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0cos s+ cost= dsin (stt over 2) sin (st over 2)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0= sin a sin b ^2 reason : simplified

Loser66
 one year ago
Best ResponseYou've already chosen the best response.1\(cos (ab) = cos a cos b + sina sinb\\cos(a+b) = cosa cos b sinasinb\\\\\dfrac{cos(ab)  cos(a+b)}{2} =\dfrac{ cosacosb+sinasinbcosacosb +sinasinb}{2}\\=\dfrac{\cancel {2} sinasinb}{\cancel 2}= sinasinb ~~=\text{left hand side}\)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0So thats for the second part that i had gotten wrong right?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0the first part was correct so i should keep that right? what about the reasonings?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I really appreciate your help by the way :)

Loser66
 one year ago
Best ResponseYou've already chosen the best response.1\[cos (ab) = cos a cos b + sina sinb ~~~~~(\text{identity})\\cos(a+b) = cosa cos b sinasinb~~~(\text{identity})\\\\\dfrac{cos(ab)  cos(a+b)}{2} \\=\dfrac{ cosacosb+sinasinbcosacosb +sinasinb}{2}~~(\text{open parentheses}) \\=\dfrac{\cancel {2} sinasinb}{\cancel 2}= sinasinb ~~=\text{left hand side}\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Thank you so much @Loser66, you're such a legend
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