Question

exact cos 11pi/3

Answer 1

@mirrorimagemirage: I'm wondering: did you and I work on this problem on Saturday or Sunday, or am I remembering the wrong person?

Answer 2

pi=180


11pi/3 = 11(180) / 3 = 660

cos(660)=cos(720-60)

Answer 3

It was you mathmale haha

Answer 4

can you take it from there?

Answer 5

@mathmale oh my bad i asked the wrong question oops!

Answer 6

What we need to determine first is the "reference angle" of 11Pi/3. What is the smallest angle which has the same trig functions and same end point as does 11Pi/3?

Answer 7

thank you for answering everyone

Answer 8

@mirrorimagemirage

cos(720)=cos(360+cos360)=cos(360) cos(360) - sin(360) sin(360)

RULE ---> cos(A+B)=cos A cos B - sin A sin B

sin 360= 0
cos 360 = 1

Good luck! I am going offline. BYE EVERYONE !!!!!!!!!!!!!!

Answer 9

Do you need further help with this problem?