Is cos(x - (pi/2)) equal to cos(x)tan(x)?

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The equation cos(x - (pi/2)) simplifies to sin(x), as cos(y) becomes zero when y equals pi/2. The original identity being tested, cos(x)tan(x), needs to be evaluated to verify if it equals sin(x). By substituting tan(x) with sin(x)/cos(x), the right side can be rewritten, leading to a comparison with sin(x). Ultimately, the identity does not hold true, as the two sides are not equal.
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cos(x-(pie/2))=cos(x)tan(x)

I have to verify this identity and can't seem to figure it out. cos (x-y)=cos x * cos y + sin x * sin y
well since cos y = 0, it kind of eliminates that side of the equation and I end up with sinx * sin1
Did I go about this all wrong?
 
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It is sin(x)*1 not sin 1, because sin(pi/2)=1. So far you have cos(x-pi/2)=sin(x), which is correct. Now write out the right hand side of your original equation and see what you get.
 
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