## lilsis76 2 years ago express sin(17pi/12) in terms of rational numbers and radicals. how can i do this :/

1. lilsis76

@anikay think u can help me with this one?

2. anikay

remember what I said about pi/6?

3. lilsis76

er.....hold on, u said....pi//6 is 30 deg.

4. lilsis76

@anikay

5. anikay

ok, so, what would 12 be? then?

6. lilsis76

let me draw it reallyfast

7. anikay

you're going to need to know your half angle formulas for this

8. lilsis76

ugh. i forgot it :/

9. anikay

well, sucks, because it's gonna be a 75 degree reference angle :P

10. lilsis76

hold on im looking up the formula

11. lilsis76

cos(2a)=cos^2 - sine^2 = 2cos^2 - 1 = 1 -2 sin^2

12. lilsis76

right? @anikay

13. anikay

awww D: no that's double angle

14. lilsis76

okay hold on let me check again

15. anikay

at least, the cos(2a) is

16. lilsis76

okay i got it, sin Q = 2 sin Q/2 cos Q/2, right?

17. anikay

uh, here

18. lilsis76

haha im not good at math seriously ugh, this is horrible. im sorry if im wasting your time

19. anikay

meh tryin to hit multiple problems

20. lilsis76

haha thank you

21. anikay

ok so its

22. anikay

$\cos ^2 \frac{ \theta }{ 2 } = \frac{ 1+\cos(\theta) }{ 2 }$

23. lilsis76

hm...okay, do i ....just plug in the 17pi/12?

24. anikay

uh....im tired xD

25. anikay

imma go with no

26. anikay

imma say plug in 150

27. lilsis76

okay :/ then ill skip it

28. lilsis76

why 150?

29. anikay

cuz 150/2 = 75 xD or you could try 17pi/6

30. lilsis76

haha where is the 17 pi coming froM?!

31. anikay

32. anikay

but multiplied by 2?

33. lilsis76

IT IS!!! haha i finally saw it haha

34. lilsis76

okay i have one more problem and its my last.

35. anikay

yesh?

36. anikay

I should sleep soon.... is this a better pastime than League of Legends? xD