Question

Use the unit circle to evaluate the followingHow do I solve this problem?

Answer 1

Notice that:

`\cos ((4\pi)/(3))=\cos (\pi+(\pi)/(3))\text{.}`

Recall that:

`\cos (\pi+x)=-\cos (x)\text{.}`

Therefore:

`\cos ((4\pi)/(3))=-\cos ((\pi)/(3))=-(1)/(2)\text{.}`

Answer:

`cos((4\pi)/(3))=-(1)/(2)\text{.}`