### Home > INT3 > Chapter 12 > Lesson 12.1.1 > Problem12-13

12-13.

If $\pi<θ<\frac{3\pi}{2}$, what is the sign of each expression?

You are in the third quadrant.

What are the signs of $x$ and $y$ in the third quadrant?

1. $\operatorname { sin } ( \theta )$

The $y$-values are negative.

1. $\operatorname { cos } ( \theta )$

Use the same method as part (a). It might also help to think about how the $\sin(x)$ and $\cos(x)$ graphs relate to each other.

1. $\operatorname { tan } ( \theta )$

Use the same method as part (a).

Negative

1. $\frac { 1 } { \operatorname { cos } ( \theta ) }$

Does taking the reciprocal of something change its sign?