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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!
 one year ago
 one year 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!
 one year ago
 one year 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
 one year ago

glucy7 Group TitleBest ResponseYou've already chosen the best response.1
thank you!!
 one year ago

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

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

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

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

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

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

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