### Home > CCA2 > Chapter 10 > Lesson 10.1.4 > Problem10-69

10-69.

Use reference angles, the symmetry of a circle, and the knowledge that cos$(\frac { \pi } { 3 })=\frac { 1 } { 2 }$ to write three other true statements using cosine and angles that are multiples of $\frac { \pi } { 3 }$. Homework Help ✎

Draw a unit circle diagram for the given angle.

Reflect the triangle in each of the $4$ quadrants. Quadrant $2$ is shown for you.

$\text{cos}\left( \frac{2\pi}{3} \right)=-\frac{1}{2}$