The inverse cos of 1, ie cos^{-1}(1) is a very special value for the inverse cosine function. Remember that cos ^{-1}(x) will give you the angle whose cosine is x

### The Value of the Inverse **Cos of 1**

As you can see below, the inverse cos^{-1} (1) is 0° or, in radian measure, 0 . '1' represents the **maximum** value of the cosine function. It happens at 0 and then again at 2Π, 4Π, 6Π etc..
(see second graph below.)

Below is a picture of the graph of cos(x) with over the domain of 0 ≤x ≤4Π with cos^{-1}(1) indicted by the black dot. As you can see from the graph below, cosine has a value of -1 at 0 and again at 2Π and 4Π and every 2Π thereafter.

### The Value of the Inverse **Cos of -1**

As you can see below, the cos^{-1} (1) is 270° or, in radian measure, 3Π/2 . '-1' represents the **minimum** value of the cosine function ever gets and happens at Π and then again at 3Π ,at 5Π etc..
(See graph at bottom )

Below is a picture of the graph of cos(x) with over the domain of 0 ≤x ≤4Π with cos^{-1}(-1) indicted by the black dot.