Answer:
First we need to determine what cos is asking for. Using Soh Cah Toa we can tell that we are using adjacent (a) and hypotenuse (h). The leg that is adjacent to Q is equal to 10 while the hypotenuse is equal to 21.
[tex]cos(Q)=\frac{adjacent}{hypotenuse}[/tex]
[tex]cos(Q) = \frac{10}{21}[/tex]
After getting to this part, we have to take the inverse of cos in order to cancel the cos on the left and leave Q by itself.
[tex]cos^{-1}(cos(Q))=cos^{-1}(\frac{10}{21})[/tex]
[tex]Q = 61.56\ degrees[/tex]
In the end we are left with that our angle Q is equal to 61.56 degrees.
Hope this helps! Let me know if you have any questions
