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Nnesha (nnesha):
rewrite tan and cot in terms of sin cos
OpenStudy (anonymous):
(sin x)(tan x cos x - cot x cos x) = 1 - 2 cos^2x
OpenStudy (anonymous):
(sinx)(sinx/cosx cosx- cosx/sinx cosx)
OpenStudy (anonymous):
what do i do next
Nnesha (nnesha):
\[\large\rm \sin(x)(\frac{\sin x}{cosx} * cosx -\frac{\cos x }{sinx } *\cos x) \]
first solve the parentheses
sinx/cos times cos x = ?
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OpenStudy (anonymous):
sinx
OpenStudy (anonymous):
\[sinx(sinx-\cos^2x /sinx)\]
Nnesha (nnesha):
right cos cancel out \[\large\rm \sin(x)(\frac{\sin x}{\cancel{cosx}} *\cancel{ cosx} -\frac{\cos x }{sinx } *\cos x) \]
\[\large\rm \sin(x)( sin x -\frac{\cos x }{sin x } *\cos x) \]
now you can distribute
by sinx
Nnesha (nnesha):
right
OpenStudy (anonymous):
\[\sin^2x-\cos^2x\]
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Nnesha (nnesha):
\[\rm sinx ( sinx - \frac{\cos^2x}{sinx})\]
multply both terms in the parentheses by sin x
Nnesha (nnesha):
oh wow nice that's right
OpenStudy (anonymous):
what do i do from there
Nnesha (nnesha):
now we can use the identity \[\huge\rm sin^2 \theta + \cos^2 \theta = 1\] solve this identity for sin^2x
OpenStudy (anonymous):
\[\sin^2x=1-\cos^2x\]
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OpenStudy (anonymous):
i get it now thank you
Nnesha (nnesha):
nice !!
we can replace sin^2x with 1-cos^2x
\[\huge\rm \color{Red}{sin^2x}-\cos^2x\]
\[\huge\rm \color{Red}{(1- \cos^2x)}-\cos^2x\]
now combine like terms