- #1
Stevo6754
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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 I am 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..