### Home > PC > Chapter 4 > Lesson 4.1.3 > Problem4-41

4-41.

Find the exact values of the following trig expressions.

1. $\text{cos}\frac { 3 \pi } { 4 }$

1. This is the 2nd quadrant.
2. Cosine is the $x$-value.
3. Cosine is negative in the 2nd quadrant.

1. $\text{sin} \frac { 11 \pi } { 6 }$

1. Sine is $y$-value.
2. What are the side lengths?
3. Is it positive or negative?

1. $\text{sin}( - \frac { 2 \pi } { 3 } )$

1. $\text{tan} \frac { 5 \pi } { 4 }$

1. Be sure to take the ratio of $\frac{y-\text{side}}{x-\text{side}}.$