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glucy7
Group Title
Find the exact value by using a halfangle identity.
cos(5π/12)
I know someone knows how to do this! if you could explain too, that'd be great!
 2 years ago
 2 years ago
glucy7 Group Title
Find the exact value by using a halfangle identity. cos(5π/12) I know someone knows how to do this! if you could explain too, that'd be great!
 2 years ago
 2 years ago

This Question is Closed

anas2000 Group TitleBest ResponseYou've already chosen the best response.1
os 5π/12 cos ((5 pi/6)/2) = +/ sqrt( (1+cos (5 pi/6))/2 ) cos(5 pi/6) = sqrt(3)/2 cos (5 pi/12) = +/ sqrt( (2/2sqrt(3)/2)/2 ) cos (5 pi/12) = +/ sqrt( ((2sqrt(3))/2)/2 ) cos (5 pi/12) = sqrt( ( (2sqrt(3))/4 ) ) 5 pi/12 is in quadrant 1 so we choose the + sign because cos is positive there
 2 years ago

anas2000 Group TitleBest ResponseYou've already chosen the best response.1
your welcome
 2 years ago

glucy7 Group TitleBest ResponseYou've already chosen the best response.1
wait did you like reexpand the problem after cos(5 pi/6) = sqrt(3)/2
 2 years ago

Dwade03 Group TitleBest ResponseYou've already chosen the best response.0
most of these problems are some identities written on the unit circle.
 2 years ago

glucy7 Group TitleBest ResponseYou've already chosen the best response.1
okay.. well can you please explain each of the steps this person just gave me? i would reaaaalllyyyy appreciate it
 2 years ago

Dwade03 Group TitleBest ResponseYou've already chosen the best response.0
ok so 5pi/12 is 75 degrees rite
 2 years ago

glucy7 Group TitleBest ResponseYou've already chosen the best response.1
i guess.. lol is it?
 2 years ago

Dwade03 Group TitleBest ResponseYou've already chosen the best response.0
pi is 180 degrees.lol you know that rite and u muliply tht by 5 and get 900 and divide 12 and you get 75 degrees
 2 years ago

glucy7 Group TitleBest ResponseYou've already chosen the best response.1
okay but what does the 75 degrees have to do with the formula?
 2 years ago

Dwade03 Group TitleBest ResponseYou've already chosen the best response.0
just to make ur question simpler... for example lets say it asked u for the cos of pi/6 which is 30 degrees.
 2 years ago

Dwade03 Group TitleBest ResponseYou've already chosen the best response.0
there is some thing called the unit circle and it has this angles from 30,45,60,90 upto 360.. and since we have cos of Pi/6 which is 30 degrees. we can look at the unit circle for the cosine of 30 degrees and find it
 2 years ago

AFleming42 Group TitleBest ResponseYou've already chosen the best response.0
@Dwade03 WHATS THE ANSWER?! D:
 2 years ago

AFleming42 Group TitleBest ResponseYou've already chosen the best response.0
how is it done using half angle identity formula?!
 2 years ago

Dwade03 Group TitleBest ResponseYou've already chosen the best response.0
ok so since they asked for cos(75) we can use the formula of using two angles to create that angle of 75. in this case we can use cos(45+35). u get tht?
 2 years ago

Lukecrayonz Group TitleBest ResponseYou've already chosen the best response.0
@ganeshie8
 2 years ago
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