Question

Find the exact value of cos 2π/3.

Answer 1

i have been stuck on this problem for like 10 min now

Answer 2

pi/3 radians = 60 degrees, and cos is looking for the side adjacent to the 60 degree angle
in a 30-60-90 triangle, the sides are in the ratio 1-sqrt(3)-2
so cos 60 = 1/2

2(pi/3) = 120 degrees-- the same triangle, except now, x is negative ==> cos 2pi/3 = -1/2

Answer 3

dang i was so close i got -1/2 i was about to turn in my assignment

Answer 4

gr8

Answer 5

thank you

Answer 6

you are aways wel come.