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## Homework Statement

Use a graphing calculator to test whether the following is an identity. If it is an identity, verify it. If it is not an identity, find a value of x for which both sides are defined but not equal.

[tex]\frac{cos(-x)}{sin(x)cot(-x)}[/tex]=1

## Homework Equations

None

## The Attempt at a Solution

Ok, plug in the left side for y1, right side for y2, obviously not an identity. The second part where it ask for a x value is where Im having trouble. I thought maybe simplify the left hand side and find a value for whatever that is that equals 1..

Cos(-x)/sin(X)(1/-tan(X))

Cos(x)/sin(x)(-cosx/sinx)

Cos(x)/-cos(x)

Cos(x)/1-sin(x)

Cos(x)-Sin(x)cos(x)

Factor out to get

1-sin(x)

ok so now I have 1-sin(x)=1

-sin(x)=0

so find the value where -sin(x)=0??

The teachers answer is - Not an identity, x=[tex]\pi/4[/tex]

Im clueless about the second part I guess..