Question

For angle theta with the point (-20,-21) on it’s terminating side, what is the value of cosine

Answer 1

`\bf (\stackrel{\stackrel{adjacent}{x}}{-20}~,~\stackrel{\stackrel{opposite}{y}}{-21})\impliedby \textit{let's find the \underline{hypotenuse}} \\\\\\ \textit{using the pythagorean theorem} \\\\ c^2=a^2+b^2\implies c=√(a^2+b^2) \qquad \begin{cases} c=hypotenuse\\ a=adjacent\\ b=opposite\\ \end{cases} \\\\\\ c=√((-20)^2+(-21)^2)\implies c=√(841)\implies c=29 \\\\\\ cos(\theta )=\cfrac{\stackrel{adjacent}{-20}}{\stackrel{hypotenuse}{29}}`