Evaluate without using a calculator, leaving the answers in exact form. $\cos \frac { 2 \pi } { 3 }$
A) $\frac { \sqrt { 3 } } { 2 }$
B) $\frac { \sqrt { 2 } } { 2 }$
C)1
D) $\frac { 1 } { 2 }$
E) $- \frac { 1 } { 2 }$

Question

Quizplus · Accepted Answer

The cosine of $ \frac { 2 \pi } { 3 } $ is equivalent to the cosine of 120 degrees, which is $- \frac { 1 } { 2 }$. This is because $ \frac { 2 \pi } { 3 } $ radians is located in the second quadrant where cosine values are negative.

Evaluate Without Using a Calculator, Leaving the Answers in Exact cos⁡2π3\cos \frac { 2 \pi } { 3 }cos32π​

Evaluate Without Using a Calculator, Leaving the Answers in Exact $\cos \frac { 2 \pi } { 3 }$