Question

How do you find the value for `cos (cos^-1 (3/4))`?

Answer 1

`cos^(-1)(x)` or `arccos(x)` (to avoid confusion as to an interpretation as a possible negative exponent)
`color(white)("XXXX")` `=`the angle `theta` for which `cos(theta) = x` (basic definition)

Therefore `cos(arccos(3/4))`
`color(white)("XXXX")` `= cos(`the angle `theta` for which `cos(theta) = 3/4 )`
`color(white)("XXXX")` `=3/4`