1 Answer

Emad Ha · Answer 1 · 2023-10-09T20:27:06+0000

we have

To find cos 45° we must first find the adjacent and the hypotenuse, so:

let x = adjacent

$\begin{gathered} \tan 45=(opposite)/(adjacent) \\ \tan 45=(9)/(x) \\ x=(9)/(\tan 45) \\ x=9 \end{gathered}$

then find the hypotenuse h:

$\begin{gathered} h^2=9^2+9^2 \\ h^2=81+81 \\ h^2=162 \\ h=\sqrt[]{162} \\ h=9\sqrt[]{2} \end{gathered}$

therefore, cos 45 is:

$\begin{gathered} \cos 45=(adjacent)/(hypotenuse) \\ \cos 45=\frac{9}{9\sqrt[]{2}} \\ \cos 45=\frac{1}{\sqrt[]{2}} \end{gathered}$

answer: C

Please log in or register to add a comment.