A community for students.
Here's the question you clicked on:
 0 viewing
 2 years ago
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
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!

This Question is Closed

anas2000
 2 years ago
Best ResponseYou've already chosen the best response.1os 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

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

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

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

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

Dwade03
 2 years ago
Best ResponseYou've already chosen the best response.0pi 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

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

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

Dwade03
 2 years ago
Best ResponseYou've already chosen the best response.0there 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

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

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

Dwade03
 2 years ago
Best ResponseYou've already chosen the best response.0ok 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?

KrissieG123
 one month ago
Best ResponseYou've already chosen the best response.0so what in the world is the final answer? Is it cos(75)?
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.