How do you prove $Cos(x-(3pi)/2)=-sinx$ ?

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Answer 1 · 2016-02-12T01:58:33

Using the identities

We have:

$cos(x-(3pi)/2) = cos((x-pi)-pi/2)$

$=sin(x-pi)$

$=sin((x-pi/2)-pi/2)$

$=-cos(x-pi/2)$

$=-sin(x)$

How do you prove Cos(x-(3pi)/2)=-sinxCos(x-(3pi)/2)=-sinx?