Evaluate Without Using a Calculator by Using Ratios in a Reference

question 276

Multiple Choice

Evaluate without using a calculator by using ratios in a reference triangle.
- $\cos \frac { 5 \pi } { 3 }$

• A) \(- \frac { \sqrt { 2 } } { 2 }\)
• B) \(\frac { \sqrt { 3 } } { 2 }\)
• C) \(- \frac { \sqrt { 3 } } { 2 }\)
• D) \(\frac { 1 } { 2 }\)