What is the value of cos inverse infinity?

Answer 1

cos^-1(infinity) = the angle whose cosine = infinity

it doesn't exist, as all angles have cosines between -1 and +1

maybe the question was intended to ask what is the cosine of infinity, or an angle approaching infinity. It also doesn't exist, as the cosine of angles approaching infinity will oscillate between 1 and -1. never approaching any number as the limit. Euler though may have another solution. Best I remember, it may be 0, the average of the oscillating numbers. Euler was the most prolific mathematician in history, and brilliant, but his solution may require interpreting the problem slightly differently.