What is the definition of the cosine function in relation to a right triangle using the adjacent side and hypotenuse?

\( \frac { \sin A } { 1 + \cos A } + \frac { 1 - \operatorname { cosec } A } { \sin A } = 2 \operatorname { cosec } A \)

\begin{tabular}{l} Resoluer el siguiente triangub. \\ \hline \( 5^{\circ} \) \\ \( \sin \alpha \)\end{tabular}\( \frac{B}{\operatorname{sen} \beta} \)

Without using a calculator, compute the sine and cosine of \( \frac{3 \pi}{4} \) by using the refer What is the reference angle? \( \square \) radians. In what quadrant is this angle? \( \sin \left(\frac{3 \pi}{4}\right)=\square \) \( \cos \left(\frac{3 \pi}{4}\right)=\square \)

If \( \theta=-\frac{2 \pi}{3} \), then find exact values for the following: \( \sin (\theta)=\square \) \( \cos (\theta)=\square \) \( \tan (\theta)=\square \) \( \csc (\theta)=\square \) \( \sec (\theta)=\square \) \( \cot (\theta)=\square \)

Without using a calculator, compute the sine and cosine of \( 120^{\circ} \) by using the reference angle. What is the reference angle? \( \square \) degrees. In what quadrant is this angle? \( \square \) (answer \( 1,2,3 \), or 4 )