how do i use cos-1
no idea
\(cos^{-1}\) is the key for the arccos function on the computer. !
Outside the calculator is \(cos^{-1}(x)=\frac{1}{cos(x)}\) !
Depends on your calculator.
cos-1 is for when you dont know what the angle is but you are given the adjacent and hypotenuse values.
For example if the hypotenuse is 10 and the adjacent is 5 you would input.
cos-1(5/10) = 60 degrees
+26 
!
