The function is .
Determine whether the function is a one to one or not for all
using horizontal line test.
Graph the function .
Observe the graph :
\Draw the horizontal line , this horizontal line touches the graph twice.
The function is not an one-to-one, because it violates the horizontal line test.
\Consider .
Graph the function on the .
Observe the graph :
\Draw the horizontal line .
The horizontal line does not touch the graph more than once.
\The function is a one-to-one, because it passes the horizontal line test.
\Assume .
Find .
If then
.
Consider .
Differentiate on each side with respect to .
Trigonometric identity: .
Therefore, .
Substitute in above expression.
.
The function is not an one-to-one for all .
The function is a one-to-one on .
Derivative of the is
.