Chapter 13 - The Trigonometric Functions - 13.1 Definitions of the Trigonometric Functions - 13.1 Exercises - Page 678: 21

$+,+,+,+,+$

- In th first quadrant where $\theta \in [0,\frac{\pi}{2}]$, the sine and cosine are both positive. - Since tangent is the ratio of sine to cosine, the tangent is positive in the first quadrant. - Since cotangent is $1$ over tangent, the cotangent is positive in the first quadrant. - Since secant is $1$ over cosine, the secant is positive in the first quadrant. - Since cosecant is $1$ over sine, the cosecant is positive in the first quadrant.