Question

The terminal side of O is in quadrant IV and sin 81. What is cose?1 1 1 흠B.D.

Answer 1

Since

$\begin{gathered} \sin \theta=-\frac{12}{13} \\ x\text{ is in the fourth quadrant, so cos }\theta\text{ is positive.} \\ \end{gathered}$$\begin{gathered} \cos \theta=\frac{\text{adjacent}}{\text{hypotenuse}} \\ adjacent^2=\sqrt[]{13^2-(-12)^2} \\ adjacent^2=25 \\ \text{adjace}nt=5 \end{gathered}$

Therefore;

$\cos \theta=\frac{5}{13}$