Answer#3

 

           

 

Notice that this inverse cosine graph has the same domain as the inverse sine but different range. (In each case the range of the inverse function is the domain to which we restricted before inverting.) Also, the inverse cosine is decreasing in a way that appears exactly opposite to the way the inverse sine is increasing. Thus it should not be surprising that their sum is a constant . You will see this proved when you read the text’s Example 10 (on page 508).