Here's the question you clicked on:
johnny101
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cos^(-1) (x) is the inverse of cos x. Its the function on top of the COS button on your calculator.
so the expression f(x)=cos x then have an inverse right? Idk why i second guessed myself
Yes, f(x) = cos x has an inverse. It is called cos^(-1)(x).
Thats why, on your calculator, on top of COS it says COS^-1..because you use that COS^-1 when you want the inverse of cos
To be very clear about this, if you want the cos of 57 degrees, you type in cos then 57 and you get your answer. If you have an angle whose cosine is .435 and you want the angle, you use COS^-1. Becuase you are going in the reverse direction, you are finding the angle (when you know the answer).